View source for Biology:Glossary of cellular and molecular biology (0–L)

{{short description|List of definitions of terms and concepts commonly used in the study of genetics}}
This '''glossary of cellular and molecular biology''' is a list of definitions of terms and concepts commonly used in the study of [[Biology:Cell biology|cell biology]], [[Biology:Molecular biology|molecular biology]], and related disciplines, including [[Biology:Genetics|genetics]], [[Biology:Microbiology|microbiology]], and [[Biology:Biochemistry|biochemistry]].<ref>{{Cite web|url=https://www.genome.gov|title=Talking Glossary of Genetic Terms|date=8 October 2017|publisher=genome.gov|access-date=8 October 2017}}</ref> It is split across two articles:
*This page, '''Glossary of cellular and molecular biology (0–L)''', lists terms beginning with numbers and with the letters A through L.
*[[Biology:Glossary of cellular and molecular biology (M–Z)|Glossary of cellular and molecular biology (M–Z)]] lists terms beginning with the letters M through Z.

The glossary is intended as introductory material for novices; for more specific and technical detail, see the article corresponding to each term. Overlapping and related glossaries include [[Biology:Glossary of evolutionary biology|Glossary of evolutionary biology]], [[Biology:Glossary of virology|Glossary of virology]], and Glossary of chemistry.

__NOTOC__

==0–9==
{{glossary}}
<span id="3'-UTR"></span>{{term|3' untranslated region (3'-UTR)}}
{{ghat|Also '''three-prime untranslated region''', '''3' non-translated region (3'-NTR)''', and '''trailer sequence'''.}}
{{defn|}}

{{term|[[Biology:Directionality (molecular biology)|3'-end]]}}{{anchor|3'}}
{{ghat|Also '''three-prime end'''.}}
{{defn|One of two ends of a single linear strand of {{gli|DNA}} or {{gli|glossary=Glossary of genetics (M–Z)|RNA}}, specifically the end at which the chain of {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} terminates at the third carbon atom in the [[Chemistry:Furanose|furanose]] ring of {{gli|deoxyribose}} or {{gli|glossary=Glossary of genetics (M–Z)|ribose}} (i.e. the terminus at which the 3' carbon is not attached to another nucleotide via a {{gli|glossary=Glossary of genetics (M–Z)|phosphodiester bond}}; ''{{gli|in vivo}}'', the 3' carbon is often still bonded to a hydroxyl group). By convention, sequences and structures positioned nearer to the 3'-end relative to others are referred to as {{gli|downstream}}. Contrast ''{{gli|5'-end}}''.}}
[[Image:Nukleotid num.svg|300px|thumb|right|A {{gli|glossary=Glossary of genetics (M–Z)|ribose}} ring with the carbon atoms numbered 1' through 5' according to chemical convention. The '''{{gli|5'-end|5' carbon}}''' is said to be ''upstream''; the '''{{gli|3'-end|3'{{nbsp}}carbon}}''' is said to be ''downstream''. Bonds to a generic {{gli|glossary=Glossary of genetics (M–Z)|nitrogenous base|base}} and a phosphate group are also shown.]]

{{term|5' cap}}
{{ghat|Also '''five-prime cap'''.}}
{{defn|A specially altered {{gli|glossary=Glossary of genetics (M–Z)|nucleotide}} attached to the {{gli|5'-end}} of some {{gli|glossary=Glossary of genetics (M–Z)|primary transcript|primary RNA transcripts}} as part of the set of {{gli|glossary=Glossary of genetics (M–Z)|post-transcriptional modifications}} which convert raw transcripts into mature RNA products. The precise structure of the 5' cap varies widely by organism; in [[Biology:Eukaryote|eukaryote]]s, the most basic cap consists of a {{gli|DNA methylation|methylated}} {{gli|guanine}} {{gli|glossary=Glossary of genetics (M–Z)|nucleoside}} bonded to the triphosphate group that terminates the 5'-end of an RNA sequence. Among other functions, capping helps to regulate the export of mature RNAs from the {{gli|glossary=Glossary of genetics (M–Z)|nucleus}}, prevent their degradation by {{gli|exonucleases}}, and promote {{gli|glossary=Glossary of genetics (M–Z)|translation}} in the cytoplasm. Mature {{gli|glossary=Glossary of genetics (M–Z)|mRNA|mRNAs}} can also be [[Biology:Messenger RNA decapping|decapped]].}}

<span id="5'-UTR"></span>{{term|5' untranslated region (5'-UTR)}}
{{ghat|Also '''five-prime untranslated region''', '''5' non-translated region (5'-NTR)''', and '''leader sequence'''.}}
{{defn|}}

{{term|5-bromodeoxyuridine}}
{{defn|See ''{{gli|BUDR|bromodeoxyuridine}}''.}}

{{term|[[Biology:Directionality (molecular biology)|5'-end]]}}{{anchor|5'}}
{{ghat|Also '''five-prime end'''.}}
{{defn|One of two ends of a single linear strand of {{gli|DNA}} or {{gli|glossary=Glossary of genetics (M–Z)|RNA}}, specifically the end at which the chain of {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} terminates at the fifth carbon atom in the [[Chemistry:Furanose|furanose]] ring of {{gli|deoxyribose}} or {{gli|glossary=Glossary of genetics (M–Z)|ribose}} (i.e. the terminus at which the 5' carbon is not attached to another nucleotide via a {{gli|glossary=Glossary of genetics (M–Z)|phosphodiester bond}}; ''{{gli|in vivo}}'', the 5' carbon is often still bonded to a [[Chemistry:Phosphate|phosphate]] group). By convention, sequences and structures positioned nearer to the 5'-end relative to others are referred to as {{gli|glossary=Glossary of genetics (M–Z)|upstream}}. Contrast ''{{gli|3'-end}}''.}}

{{term|5-methyluracil}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|thymine}}''.}}

{{glossary end}}


==A==
{{glossary}}
{{term|A chromosome}}
{{defn|}}

{{term|acentric}}
{{defn|(of a linear {{gli|chromosome}} or chromosome fragment) Having no {{gli|centromere}}.<ref name="CoG">{{cite book |last1=Klug |first1=William S. |last2=Cummings |first2=Michael R. |title=Concepts of Genetics |date=1986 |publisher=Scott, Foresman and Company |location=Glenview, Ill. |isbn=0-673-18680-6 |edition=2nd}}</ref>}}

{{term|[[Biology:Acetylation|acetylation]]}}
{{defn|}}

{{term|[[Chemistry:Acetyl-CoA|acetyl-CoA]]}}
{{defn|A molecule that participates in many {{gli|biochemistry|biochemical}} reactions in {{gli|protein}}, {{gli|carbohydrate}}, and {{gli|lipid}} {{gli|metabolism}}, notably the {{gli|citric acid cycle}}.}}

{{term|[[Biology:Acetyltransferase|acetyltransferase]]}}
{{defn|}}

{{term|acrocentric}}
{{defn|(of a linear {{gli|chromosome}} or chromosome fragment) Having a {{gli|centromere}} positioned very close to one end of the chromosome, as opposed to {{gli|glossary=Glossary of genetics (M–Z)|telocentric|at the end}} or {{gli|glossary=Glossary of genetics (M–Z)|metacentric|in the middle}}.<ref name="CoG"/>}}

{{term|[[Biology:Action potential|action potential]]}}
{{defn|The local change in [[Physics:Voltage|voltage]] that occurs when the [[Biology:Membrane potential|membrane potential]] of a specific location along the {{gli|cell membrane|membrane}} of a {{gli|cell}} rapidly depolarizes, such as when a nerve impulse is transmitted between {{gli|neuron|neurons}}.}}

{{term|activation}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|upregulation}}''.}}

{{term|[[Biology:Activator (genetics)|activator]]}}
{{defn|A type of {{gli|glossary=Glossary of genetics (M–Z)|transcription factor}} that increases the {{gli|glossary=Glossary of genetics (M–Z)|transcription}} of a {{gli|gene}} or set of genes. Most activators work by binding to a specific {{gli|glossary=Glossary of genetics (M–Z)|sequence}} located within or near an {{gli|enhancer}} or {{gli|glossary=Glossary of genetics (M–Z)|promoter}} and facilitating the binding of {{gli|glossary=Glossary of genetics (M–Z)|RNA polymerase}} and other transcription machinery in the same region. See also ''{{gli|coactivator}}''; contrast ''{{gli|glossary=Glossary of genetics (M–Z)|repressor}}''.}}

{{term|[[Biology:Active site|active site]]}}
{{ghat|Also '''binding site''' and '''catalytic site'''.}}
{{defn|The region of an {{gli|enzyme}} to which one or more {{gli|ligand|substrate molecules}} bind, causing the substrate or another molecule to undergo a chemical reaction. This region usually consists of one or more {{gli|amino acid}} residues (commonly three or four) which, when the enzyme is {{gli|glossary=Glossary of genetics (M−Z)|protein folding|folded}} properly, are able to form temporary chemical bonds with the atoms of the substrate molecule; it may also include one or more additional residues which, by interacting with the substrate, are able to catalyze a specific reaction involving the substrate. Though the active site constitutes only a small fraction of all the residues comprising the enzyme, its specificity for particular substrates and reactions is responsible for the enzyme's biological function.}}

{{term|[[Biology:Active transport|active transport]]}}
{{defn|Transport of a substance (such as a protein or {{gli|drug}}) across a {{gli|membrane|cell membrane}} against a [[Physics:Concentration gradient|concentration gradient]]. Unlike {{gli|passive transport}}, active transport requires an expenditure of energy.}}

<span id="adenine"></span>{{term|term=[[Chemistry:Adenine|adenine]]|content=[[Chemistry:Adenine|adenine]] ({{font|A|font=courier|size=large}})}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|purine}} {{gli|glossary=Glossary of genetics (M–Z)|nucleobase}} used as one of the four standard nucleobases in both {{gli|DNA}} and {{gli|glossary=Glossary of genetics (M–Z)|RNA}} molecules. Adenine forms a {{gli|base pair}} with {{gli|glossary=Glossary of genetics (M–Z)|thymine}} in DNA and with {{gli|glossary=Glossary of genetics (M–Z)|uracil}} in RNA.}}

<span id="adenosine"></span>{{term|term=[[Chemistry:Adenosine|adenosine]]|content=[[Chemistry:Adenosine|adenosine]] ({{font|A|font=courier|size=large}})}}
{{defn|One of the four standard {{gli|glossary=Glossary of genetics (M–Z)|nucleosides}} used in {{gli|glossary=Glossary of genetics (M–Z)|RNA}} molecules, consisting of an {{gli|adenine}} {{gli|base}} with its N<sub>9</sub> nitrogen {{gli|glycosidic bond|bonded}} to the C<sub>1</sub> carbon of a {{gli|glossary=Glossary of genetics (M–Z)|ribose}} sugar. Adenine bonded to {{gli|deoxyribose}} is known as {{gli|deoxyadenosine}}, which is the version used in {{gli|DNA}}.}}

<span id="ADP"></span>{{term|[[Chemistry:Adenosine diphosphate|adenosine diphosphate]] (ADP)}}
{{defn|}}

<span id="AMP"></span>{{term|[[Chemistry:Adenosine monophosphate|adenosine monophosphate]] (AMP)}}
{{defn|}}

<span id="ATP"></span>{{term|[[Chemistry:Adenosine triphosphate|adenosine triphosphate]] (ATP)}}
{{defn|An organic compound derived from {{gli|adenine}} that functions as the major source of energy for chemical reactions inside living {{gli|cells}}. It is found in all forms of life and is often referred to as the "molecular currency" of intracellular energy transfer.}}

{{term|[[Biology:A-DNA|A-DNA]]}}{{anchor|A-DNA}}
{{defn|One of three main biologically active {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid tertiary structure|structural conformations}} of the {{gli|DNA}} {{gli|double helix}}, along with {{gli|B-DNA}} and {{gli|glossary=Glossary of genetics (M–Z)|Z-DNA}}. The A-form helix has a right-handed twist with 11 {{gli|base pairs}} per full turn, only slightly more compact than B-DNA, but its bases are sharply tilted with respect to the helical axis. It is often favored in dehydrated conditions and within sequences of consecutive {{gli|glossary=Glossary of genetics (M–Z)|purine}} nucleotides (e.g. {{font|GAAGGGGA|font=courier|size=big}}); it is also the primary conformation adopted by {{gli|dsRNA|double-stranded RNA}} and {{gli|glossary=Glossary of genetics (M–Z)|RNA-DNA hybrids}}.<ref name="Ussery">Ussery, David W. "DNA Structure: A-, B-, and Z-DNA Helix Families". Lyngby, Denmark: Danish Technical University.</ref>}}

{{term|affected relative pair}}
{{defn|Any pair of organisms which are related genetically and both affected by the same {{gli|glossary=Glossary of genetics (M–Z)|trait}}. For example, two cousins who both have blue eyes are an affected relative pair since they are both affected by the {{gli|allele}} that codes for blue eyes.}}

{{term|[[Biology:Alkaline lysis|alkaline lysis]]}}
{{defn|}}

{{term|[[Biology:Allele|allele]]}}{{anchor|alleles|allelic}}
{{defn|One of multiple alternative versions of an individual {{gli|gene}}, each of which is a viable {{gli|DNA}} sequence occupying a given position, or {{gli|locus}}, on a {{gli|chromosome}}. For example, in humans, one allele of the eye-color gene produces blue eyes and another allele of the eye-color gene produces brown eyes.}}

{{term|allosome}}{{anchor|sex chromosome|sex chromosomes|allosomes}}
{{ghat|Also '''sex chromosome''', '''heterochromosome''', or '''idiochromosome'''.}}
{{defn|Any {{gli|chromosome}} that differs from an ordinary {{gli|autosome}} in size, form, or behavior and which is responsible for determining the [[Biology:Sex|sex]] of an organism. In humans, the {{gli|glossary=Glossary of genetics (M–Z)|X chromosome}} and the {{gli|glossary=Glossary of genetics (M–Z)|Y chromosome}} are sex chromosomes.}}

<span id="alpha helix"></span>{{term|alpha helix (α-helix)}}
{{defn|A common structural {{gli|glossary=Glossary of genetics (M–Z)|motif}} in the secondary structures of {{gli|glossary=Glossary of genetics (M–Z)|proteins}} consisting of a right-handed helix conformation resulting from hydrogen bonding between {{gli|amino acid}} residues which are not immediately adjacent to each other.}}

{{term|[[Biology:Alternative splicing|alternative splicing]]}}
{{ghat|Also '''differential splicing''' or simply '''splicing'''.}}
{{defn|A regulated phenomenon of eukaryotic {{gli|gene expression}} in which specific {{gli|exons}} or parts of exons from the same {{gli|glossary=Glossary of genetics (M–Z)|primary transcript}} are variably included within or removed from the final, mature {{gli|glossary=Glossary of genetics (M–Z)|mRNA|messenger RNA}} transcript. A class of {{gli|glossary=Glossary of genetics (M–Z)|post-transcriptional modification}}, alternative splicing allows a single {{gli|gene}} to code for multiple [[Biology:Protein isoform|protein isoform]]s and greatly increases the diversity of proteins that can be produced by an individual {{gli|genome}}. See also ''{{gli|glossary=Glossary of genetics (M–Z)|RNA splicing}}''.}}

{{term|[[Biology:Stop codon#Nomenclature|amber]]}}
{{defn|One of three {{gli|glossary=Glossary of genetics (M–Z)|stop codons}} used in the {{gli|glossary=Glossary of genetics (M–Z)|standard genetic code}}; in {{gli|glossary=Glossary of genetics (M–Z)|RNA}}, it is specified by the nucleotide triplet {{font|UAG|font=courier|size=big}}. The other two stop codons are named {{gli|glossary=Glossary of genetics (M–Z)|ochre}} and {{gli|glossary=Glossary of genetics (M–Z)|opal}}.}}

{{term|[[Chemistry:Amino acid|amino acid]]}}{{anchor|amino acids}}
{{defn|Any of a class of organic compounds whose basic structural formula includes a central carbon atom bonded to [[Chemistry:Amine|amine]] and carboxyl [[Chemistry:Functional group|functional group]]s and to a variable [[Chemistry:Substituent|side chain]]. Out of nearly 500 known amino acids, a set of 20 are coded for by the {{gli|glossary=Glossary of genetics (M–Z)|standard genetic code}} and incorporated into long polymeric chains as the building blocks of {{gli|glossary=Glossary of genetics (M–Z)|peptides}} and hence of {{gli|glossary=Glossary of genetics (M–Z)|polypeptides}} and {{gli|glossary=Glossary of genetics (M–Z)|proteins}}. The specific sequences of amino acids in the polypeptide chains that form a protein are ultimately responsible for determining the protein's structure and function.}}
[[File:Amino acid generic structure.png|400px|thumb|right|Every '''{{gli|amino acid}}''' has the same basic structural formula, a central "alpha" (α) carbon bonded to three major substituents: one amino group (blue), one carboxyl group (red), and one variable side chain (green). The side chain gives each particular amino acid its unique identity, and can range from a simple methyl group (alanine) to more complex functional groups such as a double-ringed indole (tryptophan). During {{gli|glossary=Glossary of genetics (M–Z)|translation}}, amino acids are joined into a linear chain by condensation reactions which create {{gli|glossary=Glossary of genetics (M–Z)|peptide bonds}} between the carboxyl group of one amino acid and the amino group of an adjacent amino acid. The first and last amino acids in the chain are said to be {{gli|glossary=Glossary of genetics (M–Z)|N-terminal}} and {{gli|C-terminal}}, respectively, in reference to the unbonded amino group of the first amino acid and the unbonded carboxyl group of the last.]]

{{term|amino terminus}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|N-terminus}}''.}}

{{term|aminoacyl-tRNA synthetase}}
{{ghat|Also '''tRNA-ligase'''.}}
{{defn|Any of a set of enzymes which catalyze the [[Chemistry:Transesterification|transesterification]] reaction that results in the attachment of a specific {{gli|amino acid}} (or a precursor) to one of its cognate {{gli|glossary=Glossary of genetics (M–Z)|tRNA|transfer RNA}} molecules, forming an {{gli|aa-tRNA|aminoacyl-tRNA}}. Each of the 20 different amino acids used in the {{gli|genetic code}} is recognized and attached by its own specific synthetase enzyme, and most synthetases are cognate to several different tRNAs according to their specific {{gli|anticodons}}.}}

<span id="aa-tRNA"></span>{{term|[[Biology:Aminoacyl-tRNA|aminoacyl-tRNA]] (aa-tRNA)}}
{{ghat|Also '''aminoacylated tRNA''' and '''charged tRNA'''.}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|transfer RNA}} to which a cognate {{gli|amino acid}} is chemically bonded; i.e. the product of a transesterification reaction catalyzed by an {{gli|aminoacyl-tRNA synthetase}}. Aminoacyl-tRNAs bind to the {{gli|A site|aminoacyl site}} of the {{gli|glossary=Glossary of genetics (M–Z)|ribosome}} during {{gli|glossary=Glossary of genetics (M–Z)|translation}}.}}

{{term|[[Biology:Amplicon|amplicon]]}}
{{defn|Any DNA or RNA sequence or fragment that is the source and/or product of an {{gli|amplification}} reaction. The term is most frequently used to describe the numerous copied fragments that are the products of the {{gli|glossary=Glossary of genetics (M–Z)|polymerase chain reaction}} or {{gli|ligase chain reaction}}, though it may also refer to sequences that are amplified naturally within a genome, e.g. by {{gli|gene duplication}}.}}

{{term|amplification}}
{{defn|The {{gli|glossary=Glossary of genetics (M–Z)|replication}} of a biomolecule, in particular the production of one or more copies of a {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence}}, known as an {{gli|amplicon}}, either naturally (e.g. by spontaneous {{gli|duplication|duplications}}) or artificially (e.g. by {{gli|glossary=Glossary of genetics (M–Z)|PCR}}), and especially implying many repeated replication events resulting in thousands, millions, or billions of copies of the target sequence, which is then said to be ''amplified''.}}

{{term|[[Biology:Anaphase|anaphase]]}}
{{defn|The stage of {{gli|glossary=Glossary of genetics (M–Z)|mitosis}} and {{gli|glossary=Glossary of genetics (M–Z)|meiosis}} that occurs after {{gli|glossary=Glossary of genetics (M–Z)|metaphase}} and before {{gli|glossary=Glossary of genetics (M–Z)|telophase}}, when the replicated chromosomes are segregated and each of the {{gli|glossary=Glossary of genetics (M–Z)|sister chromatids}} are moved to opposite sides of the {{gli|cell}}.}}

{{term|[[Biology:Anaphase lag|anaphase lag]]}}
{{defn|The failure of one or more pairs of {{gli|glossary=Glossary of genetics (M–Z)|sister chromatids}} or {{gli|homologous chromosomes}} to properly migrate to opposite sides of the cell during {{gli|anaphase}} of {{gli|glossary=Glossary of genetics (M–Z)|mitosis}} or {{gli|glossary=Glossary of genetics (M–Z)|meiosis}} due to a defective {{gli|glossary=Glossary of genetics (M–Z)|spindle apparatus}}. Consequently, both daughter cells are {{gli|aneuploid}}: one is missing one or more chromosomes (creating a {{gli|glossary=Glossary of genetics (M–Z)|monosomy}}) while the other has one or more extra copies of the same chromosomes (creating a {{gli|glossary=Glossary of genetics (M–Z)|polysomy}}).}}

{{term|aneucentric}}
{{defn|(of a linear {{gli|chromosome}} or chromosome fragment) Having an abnormal number of {{gli|centromeres}}, i.e. more than one.<ref name="DoG7"/>}}

{{term|[[Medicine:Aneuploidy|aneuploidy]]}}{{anchor|aneuploid}}
{{defn|The condition of a cell or organism having an abnormal number of one or more particular {{gli|chromosomes}} (but excluding abnormal numbers of complete sets of chromosomes, which instead is known as {{gli|euploidy}}).}}

{{term|annealing}}{{anchor|anneal|anneals|annealed}}
{{defn|The {{gli|hybridization}} of two {{gli|glossary=Glossary of genetics (M–Z)|single-stranded}} {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} molecules containing {{gli|complementary}} sequences, creating a {{gli|double-stranded}} molecule with {{gli|glossary=Glossary of genetics (M–Z)|paired}} {{gli|glossary=Glossary of genetics (M–Z)|nucleobases}}. The term is used in particular to describe steps in certain laboratory techniques such as the {{gli|glossary=Glossary of genetics (M–Z)|polymerase chain reaction}}, where double-stranded DNA molecules are repeatedly {{gli|denatured}} into single strands by heating and then exposed to cooler temperatures, causing the strands to reassociate with each other or with complementary {{gli|glossary=Glossary of genetics (M–Z)|primers}}. The exact {{gli|glossary=Glossary of genetics (M–Z)|reassociation kinetics|temperature at which annealing occurs}} is strongly influenced by the length and specific sequence of the individual strands.}}

{{term|anticodon}}{{anchor|anticodons}}
{{defn|A series of three consecutive {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} within a {{gli|glossary=Glossary of genetics (M–Z)|tRNA|transfer RNA}} which {{gli|complement}} the three nucleotides of a {{gli|codon}} within an {{gli|glossary=Glossary of genetics (M–Z)|mRNA}} transcript. During {{gli|glossary=Glossary of genetics (M–Z)|translation}}, each tRNA recruited to the {{gli|glossary=Glossary of genetics (M–Z)|ribosome}} contains a single anticodon triplet that pairs with one or more complementary codons from the mRNA sequence, allowing each codon to specify a particular {{gli|amino acid}} to be added to the growing peptide chain. Anticodons containing {{gli|inosine}} in the first position are capable of pairing with more than one codon due to a phenomenon known as {{gli|glossary=Glossary of genetics (M–Z)|wobble base pairing}}.}}

{{term|antioncogene}}
{{defn|A {{gli|gene}} which helps to regulate cell growth and suppress tumors when functioning correctly, such that its absence or malfunction can result in uncontrolled cell growth and possibly cancer.<ref name="NCI">{{cite web |title=NCI Dictionary of Genetics Terms |url=https://www.cancer.gov/publications/dictionaries/genetics-dictionary |website=National Cancer Institute |publisher=PDQ® Cancer Genetics Editorial Board}}</ref> Compare ''{{gli|glossary=Glossary of genetics (M–Z)|oncogene}}''.}}

{{term|[[Biology:Antiparallel (biochemistry)|antiparallel]]}}
{{defn|The orientation of two strands of a double-stranded {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} (and more generally any pair of [[Biology:Biopolymer|biopolymer]]s) which are parallel to each other but with opposite {{gli|directionality}}. For example, the two {{gli|complementary}} strands of a {{gli|DNA}} molecule run side-by-side but in opposite directions, with one strand oriented {{gli|5'-end|5'}}-to-{{gli|3'-end|3'}} and the other 3'-to-5'.}}

{{term|[[Physics:Antiporter|antiporter]]}}
{{defn|}}

{{term|antisense}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|template strand}}''.}}

{{term|[[Biology:Antisense RNA|antisense RNA]] (asRNA)}}{{anchor|asRNA|antisense RNA}}
{{ghat|Also '''antisense transcript''' and '''antisense oligonucleotide (ASO)'''.}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|single-stranded}} {{gli|glossary=Glossary of genetics (M–Z)|non-coding RNA}} molecule containing an {{gli|glossary=Glossary of genetics (M–Z)|sense|antisense}} sequence that is {{gli|complementary}} to a sense strand, such as a {{gli|glossary=Glossary of genetics (M–Z)|messenger RNA}}, with which it readily {{gli|hybridizes}}, thereby inhibiting the sense strand's further activity (e.g. {{gli|glossary=Glossary of genetics (M–Z)|translation}} into protein). Many different classes of naturally occurring RNA such as {{gli|glossary=Glossary of genetics (M–Z)|siRNA}} function by this principle, making them potent gene {{gli|glossary=Glossary of genetics (M–Z)|silencing|silencers}} in various {{gli|gene regulation}} mechanisms. Synthetic antisense RNA has also found widespread use in gene {{gli|knockdown}} studies, and in practical applications such as [[Biology:Antisense therapy|antisense therapy]].}}

{{term|anucleate}}
{{ghat|Also '''anuclear'''.}}
{{defn|(of a cell or organism) Lacking a {{gli|glossary=Glossary of genetics (M–Z)|nucleus}}, i.e. a discrete, membrane-bound organelle enclosing the cell's {{gli|genomic DNA}}, used especially of cells which normally have a nucleus but from which the nucleus {{gli|enucleate|has been removed}} (e.g. in artificial {{gli|glossary=Glossary of genetics (M–Z)|nuclear transfer}}), and also of specialized cell types that develop without nuclei despite that the cells of other tissues comprising the same organism ordinarily do have nuclei (e.g. mammalian erythrocytes).}}

{{term|[[Biology:Apical constriction|apical constriction]]}}
{{defn|}}

{{term|[[Biology:Apoptosis|apoptosis]]}}
{{defn|A highly regulated form of {{gli|programmed cell death}} that occurs in {{gli|multicellular}} organisms.}}

{{term|[[Biology:Aptamer|aptamer]]}}
{{defn|}}

{{term|[[Biology:Artificial gene synthesis|artificial gene synthesis]]}}
{{defn|A set of laboratory methods used in the {{gli|de novo synthesis|''de novo'' synthesis}} of a {{gli|gene}} (or any other {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence}}) from free {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}}, i.e. without relying on an existing {{gli|glossary=Glossary of genetics (M–Z)|template strand}}.}}

{{term|asynapsis}}
{{defn|The failure of {{gli|homologous chromosomes}} to properly pair with each other during {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}.<ref name="DoG7"/> Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|synapsis}}'' and ''{{gli|desynapsis}}''.}}

{{term|attached X}}
{{ghat|Also '''compound X'''.}}
{{defn|A single {{gli|glossary=Glossary of genetics (M–Z)|monocentric}} {{gli|chromosome}} containing two or more physically attached copies of the normal {{gli|glossary=Glossary of genetics (M–Z)|X chromosome}} as a result of either a natural internal {{gli|chromosomal duplication|duplication}} or any of a variety of {{gli|genetic engineering}} methods. The resulting compound chromosome effectively carries two or more doses of all genes and sequences included on the X, yet functions in all other respects as a single chromosome, meaning that haploid 'XX' {{gli|gametes}} (rather than the ordinary 'X' gametes) will be produced by {{gli|glossary=Glossary of genetics (M–Z)|meiosis}} and inherited by progeny. In mechanisms such as {{gli|genic balance}} in which the sex of an organism is determined by the total dosage of X-linked genes, an abnormal 'XXY' {{gli|glossary=Glossary of genetics (M–Z)|zygote}}, fertilized by one XX gamete and one Y gamete, will develop into a female.}}

{{term|[[Biology:Autosome|autosome]]}}{{anchor|autosomes|autosomal}}
{{defn|Any {{gli|chromosome}} that is not an {{gli|allosome}} and hence is not involved in the determination of the [[Biology:Sex|sex]] of an organism. Unlike the sex chromosomes, the autosomes in a {{gli|diploid}} cell exist in pairs, with the members of each pair having the same structure, morphology, and genetic {{gli|loci}}.}}

{{term|autozygote}}
{{defn|A cell or organism that is {{gli|homozygous}} for a {{gli|locus}} at which the two homologous {{gli|alleles}} are identical by descent, both having been derived from a single gene in a common ancestor.<ref name="DoG7"/> Contrast ''{{gli|allozygote}}''.}}

{{term|[[Biology:Auxesis|auxesis]]}}
{{defn|The growth of a multicellular organism due to an increase in the size of its cells rather than an increase in the number of cells.}}

{{term|[[Biology:Axenic|axenic]]}}
{{defn|Describing a {{gli|cell culture}} in which only a single species, variety, or strain is present, and which is therefore entirely free of contaminating organisms including symbiotes and parasites.}}

{{glossary end}}


==B==
{{glossary}}
{{term|[[Biology:B chromosome|B chromosome]]}}
{{defn|Any supernumerary {{gli|glossary=Glossary of genetics (M–Z)|nuclear DNA|nuclear DNA molecule}} which is not a duplicate of nor {{gli|homologous chromosomes|homologous}} to any of the standard complement of normal {{gli|A chromosome|"A" chromosomes}} comprising a genome. Typically very small and devoid of structural genes, B chromosomes are by definition not necessary for life. Though they occur naturally in many eukaryotic species, they are {{gli|glossary=Glossary of genetics (M–Z)|non-Mendelian inheritance|not stably inherited}} and thus {{gli|copy-number variation|vary widely in copy number}} even between closely related individuals.<ref name="DoG7"/>}}

{{term|back mutation}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|mutation}} that reverses the effect of a previous mutation which had inactivated a gene, thus restoring {{gli|glossary=Glossary of genetics (M–Z)|wild-type}} function.<ref name="Lewin">{{cite book|title=Genes VIII|last1=Lewin|first1=Benjamin|year=2003|publisher=Pearson Prentice Hall|location=Upper Saddle River, NJ|isbn=0-13-143981-2}}</ref> See also ''{{gli|glossary=Glossary of genetics (M–Z)|reverse mutation}}''.}}

{{term|[[Biology:Backcrossing|backcrossing]]}}
{{ghat|Also '''testcrossing'''.}}
{{defn|The breeding of a {{gli|hybrid}} organism with one of its parents or an individual genetically similar to one of its parents, often intentionally as a type of {{gli|glossary=Glossary of genetics (M–Z)|selective breeding}}, with the aim of producing offspring with a genetic identity which is closer to that of the parent. The reproductive event and the resulting progeny are both referred to as a ''backcross'', often abbreviated in genetics shorthand with the symbol ''BC''.}}

<span id="BAC"></span>{{term|[[Biology:Bacterial artificial chromosome|bacterial artificial chromosome]] (BAC)}}
{{defn|}}

{{term|[[Biology:Balancer chromosome|balancer chromosome]]}}
{{defn|}}

{{term|base}}
{{defn|An abbreviation of {{gli|glossary=Glossary of genetics (M–Z)|nitrogenous base}} and {{gli|glossary=Glossary of genetics (M–Z)|nucleobase}}.}}

<span id="base pair"></span>{{term|[[Biology:Base pair|base pair]] (bp)}}{{anchor|base pairs|base pairing|base-pair|pairing|paired}}
{{defn|A pair of two {{gli|glossary=Glossary of genetics (M–Z)|nucleobases}} on complementary {{gli|DNA}} or {{gli|glossary=Glossary of genetics (M–Z)|RNA}} strands which are bonded to each other by [[Chemistry:Hydrogen bond|hydrogen bond]]s. The ability of consecutive base pairs to stack one upon another contributes to the long-chain {{gli|double helix}} structures observed in both {{gli|dsDNA|double-stranded DNA}} and {{gli|dsRNA|double-stranded RNA}} molecules.}}

{{term|baseline}}
{{defn|A measure of the {{gli|gene expression}} level of a {{gli|gene}} or genes prior to a perturbation in an experiment, as in a negative control. ''Baseline expression'' may also refer to the expected or historical measure of expression for a gene.}}

<span id="BLAST"></span>{{term|[[Software:BLAST (biotechnology)|basic local alignment search tool]] (BLAST)}}
{{defn|A computer algorithm widely used in {{gli|bioinformatics}} for {{gli|glossary=Glossary of genetics (M–Z)|sequence alignment|aligning}} and comparing primary biological sequence information such as the {{gli|glossary=Glossary of genetics (M–Z)|nucleotide sequences}} of DNA or RNA or the {{gli|amino acid sequences}} of proteins. BLAST programs enable scientists to quickly check for homology between two or more sequences by directly comparing the nucleotides or amino acids present at each position within each sequence; a common use is to search for matches between a specific query sequence and a digital sequence database such as a {{gli|library|genome library}}, with the program returning a list of sequences from the database which resemble the query sequence above a specified threshold of similarity. Such comparisons can permit the identification of an organism from an unknown sample or the inference of evolutionary relationships between genes, proteins, or species.}}

{{term|B-DNA}}{{anchor|B-DNA}}
{{defn|The "standard" or classical {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid tertiary structure|structural conformation}} of the {{gli|DNA}} {{gli|double helix}} ''{{gli|in vivo}}'', thought to represent an average of the various distinct conformations assumed by very long DNA molecules under physiological conditions.<ref name="Ussery"/> The B-form double helix has a right-handed twist with a diameter of 23.7 [[Ångström|ångström]]s and a {{gli|glossary=Glossary of genetics (M–Z)|pitch}} of 35.7 ångströms or about 10.5 {{gli|base pairs}} per full turn, such that each nucleotide pair is rotated 36° around the helical axis with respect to its neighboring pairs. See also ''{{gli|A-DNA}}'' and ''{{gli|glossary=Glossary of genetics (M–Z)|Z-DNA}}''.}}
[[File:Dnaconformations.png|350px|thumb|right|The three principal biologically active conformations of {{gli|DNA}} molecules: '''{{gli|A-DNA}}''', '''{{gli|B-DNA}}''', and '''{{gli|glossary=Glossary of genetics (M–Z)|Z-DNA}}''' (left to right), as viewed from the side and down the axis of the {{gli|double helix}}.]]

{{term|bidirectional replication}}
{{defn|A common mechanism of {{gli|DNA replication}} in which two {{gli|replication forks}} move in opposite directions away from the same {{gli|origin of replication|origin}}; this results in a {{gli|replication bubble|bubble-like region}} where the {{gli|duplex}} molecule is locally separated into two {{gli|ssDNA|single strands}}.<ref name="DoG7"/>}}

{{term|[[Binary fission|binary fission]]}}
{{defn|}}

{{term|[[Biology:Binding site|binding site]]}}
{{defn|}}

{{term|[[Biology:Bioenergetics|bioenergetics]]}}
{{defn|}}

{{term|[[Biology:Biomarker|biomarker]]}}
{{defn|}}

{{term|[[Biology:Biomolecular gradient|biomolecular gradient]]}}
{{defn|}}

{{term|bivalent}}
{{defn|}}

{{term|[[Biology:Blot|blot]]}}
{{defn|Any of a variety of molecular biology methods by which {{gli|electrophoresis|electrophoretically}} or chromatographically resolved {{gli|DNA}}, {{gli|glossary=Glossary of genetics (M–Z)|RNA}}, or {{gli|glossary=Glossary of genetics (M–Z)|protein}} are transferred from a support medium such as a polyacrylamide gel onto a carrier such as an immobilizing paper or membrane matrix. Some methods involve the transfer of molecules by [[Physics:Capillary action|capillary action]] (e.g. {{gli|glossary=Glossary of genetics (M–Z)|Southern blot|Southern}} and {{gli|glossary=Glossary of genetics (M–Z)|northern blotting}}), while others rely on the transport of charged molecules by electrophoresis (e.g. {{gli|glossary=Glossary of genetics (M–Z)|western blotting}}). The transferred molecules are then visualized by colorant staining, autoradiography, or the selective {{gli|labelling}} of molecules containing specific sequences or epitopes with {{gli|hybridization probes}} or antibodies bound to a chemiluminescent reporter.<ref name="DoG7"/>}}

{{term|[[Biology:Sticky and blunt ends|blunt end]]}}
{{defn|}}

<span id="bUDR"></span>{{term|[[Chemistry:Bromodeoxyuridine|bromodeoxyuridine]] (BUDR, BrdU)}}
{{ghat|Also '''5-bromodeoxyuridine'''.}}
{{defn|}}

{{glossary end}}


==C==
{{glossary}}
{{term|[[Biology:Cadastral gene|cadastral gene]]}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|regulatory}} {{gli|gene}} that restricts the {{gli|expression}} of other genes to specific tissues or body parts in an organism, typically by producing {{gli|gene products}} which variably inhibit or permit {{gli|glossary=Glossary of genetics (M–Z)|transcription}} of the other genes in different cell types.<ref name="DoG7"/> The term is used most commonly in [[Biology:Plant genetics|plant genetics]].}}

{{term|[[Biology:Cadherin|cadherin]]}}{{anchor|cadherins}}
{{defn|}}

{{term|[[Medicine:Callus|callus]]}}
{{defn|}}

{{term|[[Biology:Calvin cycle|Calvin cycle]]}}
{{defn|}}

{{term|[[Biology:Candidate gene|candidate gene]]}}{{anchor|candidate genes}}
{{defn|A {{gli|gene}} whose location on a chromosome is {{gli|genetic association|associated}} with a particular {{gli|glossary=Glossary of genetics (M–Z)|phenotype}} (often a disease-related phenotype), and which is therefore suspected of causing or contributing to the phenotype. Candidate genes are often selected for study based on ''a priori'' knowledge or speculation about their functional relevance to the trait or disease being researched.}}

{{term|canonical sequence}}
{{defn|See ''{{gli|consensus sequence}}''.}}

{{term|carboxyl terminus}}
{{defn|See ''{{gli|C-terminus}}''.}}

{{term|CCAAT box}}
{{ghat|Also '''CAAT box''' or '''CAT box'''.}}
{{defn|A highly {{gli|conserved sequence|conserved}} {{gli|glossary=Glossary of genetics (M–Z)|regulatory}} DNA sequence located approximately 75 base pairs {{gli|glossary=Glossary of genetics (M–Z)|upstream}} (i.e. -75) of the site of the start of {{gli|glossary=Glossary of genetics (M–Z)|transcription}} for many eukaryotic genes.<ref name="CoG"/>}}

{{term|cDNA}}
{{defn|See ''{{gli|cDNA|complementary DNA}}''.}}

{{term|[[Biology:Cell|cell]]}}{{anchor|cells}}
{{defn|}}

{{term|[[Biology:Cell biology|cell biology]]}}
{{ghat|Also '''cellular biology'''.}}
{{defn|The branch of [[Biology:Biology|biology]] that studies the structures, functions, processes, and properties of biological {{gli|cells}}, the self-contained units of life common to all living organisms.}}

<span id="cell compartmentalization"></span>{{term|cell compartmentalization}}
{{defn|The subdivision of the interior of a {{gli|cell}} into distinct, usually membrane-bound compartments, including the {{gli|nucleus}} and {{gli|organelles}} ({{gli|endoplasmic reticulum}}, {{gli|mitochondria}}, {{gli|chloroplasts}}, {{gli|vesicle|intracellular vesicles}}, etc.), a defining feature of the Eukarya.<ref name="MacLean"/>}}

{{term|[[Biology:Cell cortex|cell cortex]]}}
{{defn|A specialized layer of {{gli|cytoplasmic}} proteins lining the inner face of the {{gli|cell membrane}} in most eukaryotic cells, composed primarily of {{gli|actin}} {{gli|glossary=Glossary of genetics (M−Z)|microfilaments}} and {{gli|glossary=Glossary of genetics (M−Z)|myosin}} {{gli|glossary=Glossary of genetics (M−Z)|motor proteins}} and usually 100–1000 nanometres thick, which functions as a modulator of membrane behavior and cell surface properties.}}

{{term|[[Biology:Cell counting|cell counting]]}}
{{defn|}}

{{term|[[Biology:Cell culture|cell culture]]}}
{{defn|The process by which living cells are grown and maintained, or "cultured", under carefully controlled conditions, generally outside of their natural environment. Optimal growth conditions vary widely for different cell types but usually consist of a suitable vessel (e.g. a {{gli|culture tube}} or {{gli|Petri dish}}) containing a specifically formulated {{gli|substrate}} or {{gli|growth medium}} that supplies all of the nutrients essential for life ({{gli|amino acids}}, {{gli|carbohydrates}}, vitamins, minerals, etc.) plus any desirable growth factors and {{gli|hormones}}, permits gas exchange (if necessary), and regulates the environment by maintaining consistent physico-chemical properties (e.g. {{gli|pH}}, osmotic pressure, and temperature). Some cell types require a solid surface to which they can adhere in order to reproduce, while others can be grown freely floating in a liquid or gelatinous {{gli|suspension culture|suspension}}. Most cells have a genetically determined reproduction limit, but {{gli|immortalized}} cells will divide indefinitely if provided with optimal conditions.}}

{{term|[[Biology:Cell cycle|cell cycle]]}}
{{defn|}}

{{term|[[Biology:Cell division|cell division]]}}
{{defn|}}

{{term|[[Biology:Cell fusion|cell fusion]]}}
{{defn|}}

{{term|[[Biology:Cell membrane|cell membrane]]}}
{{defn|}}

{{term|[[Biology:Cell physiology|cell physiology]]}}
{{defn|}}

{{term|[[Biology:Cell polarity|cell polarity]]}}
{{defn|}}

{{term|[[Biology:Cell signaling|cell signaling]]}}
{{defn|}}

{{term|[[Biology:Cell wall|cell wall]]}}
{{defn|}}

<span id="cfDNA"></span>{{term|cell-free DNA (cfDNA)}}
{{defn|Any {{gli|DNA}} molecule that exists outside of a {{gli|cell}} or {{gli|glossary=Glossary of genetics (M–Z)|nucleus}}, freely floating in an [[Biology:Extracellular fluid|extracellular fluid]] such as [[Biology:Blood plasma|blood plasma]].}}

{{term|cellular}}
{{defn|}}

{{term|[[Biology:Cellular differentiation|cellular differentiation]]}}
{{defn|}}

{{term|cellular immunity}}
{{defn|}}

{{term|[[Biology:Cellular noise|cellular noise]]}}
{{defn|}}

{{term|cellular reprogramming}}
{{defn|The conversion of a fully {{gli|cellular differentiation|differentiated}} {{gli|cell}} from one {{gli|tissue}}-specific cell type to another. This involves {{gli|dedifferentiation}} to a {{gli|pluripotent}} state; an example is the conversion of mouse {{gli|somatic cells}} to an undifferentiated embryonic state, which relies on the transcription factors ''Oct4'', ''Sox2'', ''[[Biology:Myc|Myc]]'', and ''Klf4''.<ref>{{cite journal |last1=Nishikawa |first1=S. |title=Reprogramming by the numbers |journal=Nature Biotechnology |date=2007 |volume=25 |issue=8 |pages=877–878|doi=10.1038/nbt0807-877 |pmid=17687365 |s2cid=39773318 }}</ref>}}

{{term|[[Biology:Cellular senescence|cellular senescence]]}}
{{defn|}}

<span id="centimorgan"></span>{{term|[[Biology:Centimorgan|centimorgan]] (cM)}}
{{ghat|Also '''map unit (m.u.)'''.}}
{{defn|A unit for measuring {{gli|linkage|genetic linkage}} defined as the distance between chromosomal {{gli|loci}} for which the expected average number of intervening {{gli|chromosomal crossovers}} in a single generation is 0.01. Though not an actual measure of physical distance, it is used to infer the actual distance between two loci based on the apparent likelihood of a crossover occurring between them.}}

{{term|[[Biology:Central dogma of molecular biology|central dogma of molecular biology]]}}
{{defn|A generalized framework for understanding the flow of genetic information between macromolecules within biological systems. The central dogma outlines the fundamental principle that the sequence information encoded in the three major classes of [[Biology:Biopolymer|biopolymer]]—{{gli|DNA}}, {{gli|glossary=Glossary of genetics (M–Z)|RNA}}, and {{gli|glossary=Glossary of genetics (M–Z)|protein}}—can only be transferred between these three classes in certain ways, and not in others: specifically, information transfer between the {{gli|glossary=Glossary of genetics (M–Z)|nucleic acids}} and from nucleic acid to protein is possible, but transfer from protein to protein, or from protein back to either type of nucleic acid, is impossible and does not occur naturally.}}
[[File:Central dogma of molecular biology colorized+special transfer.png|thumb|350px|right|Possible types of information transfer according to the '''{{gli|central dogma of molecular biology}}'''. Three general transfers, in red, occur routinely in all living cells: DNA-to-DNA ({{gli|DNA replication}}), DNA-to-RNA ({{gli|glossary=Glossary of genetics (M–Z)|transcription}}), and RNA-to-protein ({{gli|glossary=Glossary of genetics (M–Z)|translation}}). Three special transfers, in blue, are known to occur only in viruses or in the laboratory: RNA-to-RNA ({{gli|glossary=Glossary of genetics (M–Z)|RNA replication}}), RNA-to-DNA ({{gli|glossary=Glossary of genetics (M–Z)|reverse transcription}}), and DNA-to-protein (direct translation without an mRNA intermediate). An additional three transfers are believed not to be possible at all: protein-to-protein, protein-to-RNA, and protein-to-DNA—though it has been argued that there are exceptions by which all three can occur.]]

{{term|[[Biology:Centriole|centriole]]}}{{anchor|centrioles}}
{{defn|A cylindrical {{gli|organelle}} composed of {{gli|microtubules}}, present only in certain eukaryotes. A pair of centrioles migrate to and define the two opposite poles of a {{gli|cell division|dividing cell}} where, as part of a {{gli|centrosome}}, they initiate the growth of the {{gli|spindle apparatus}}.}}

{{term|[[Biology:Centromere|centromere]]}}{{anchor|centromeres}}
{{defn|A specialized DNA sequence within a {{gli|chromosome}} that links a pair of {{gli|glossary=Glossary of genetics (M–Z)|sister chromatids}}. The primary function of the centromere is to act as the site of assembly for {{gli|kinetochores}}, protein complexes which direct the attachment of {{gli|glossary=Glossary of genetics (M–Z)|spindle apparatus|spindle fibers}} to the centromere and facilitate {{gli|glossary=Glossary of genetics (M–Z)|segregation}} of the chromatids during {{gli|glossary=Glossary of genetics (M–Z)|mitosis}} or {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}.}}

{{term|centromeric index}}
{{defn|The proportion of the total length of a {{gli|chromosome}} encompassed by its {{gli|glossary=Glossary of genetics (M–Z)|short arm}}, typically expressed as a percentage; e.g. a chromosome with a centromeric index of 15 is {{gli|acrocentric}}, with a short arm comprising only 15% of its overall length.<ref name="DoG7"/>}}

{{term|[[Biology:Centrosome|centrosome]]}}{{anchor|centrosomes}}
{{defn|}}

{{term|cfDNA}}
{{defn|See ''{{gli|cell-free DNA}}''.}}

{{term|[[Biology:Chargaff's rules|Chargaff's rules]]}}
{{defn|A set of axioms which state that, in the {{gli|DNA}} of any chromosome, species, or organism, the total number of {{gli|adenine}} ({{font|A|font=courier|size=big}}) {{gli|glossary=Glossary of genetics (M–Z)|residues}} will be approximately equal to the total number of {{gli|glossary=Glossary of genetics (M–Z)|thymine}} ({{font|T|font=courier|size=big}}) residues, and the number of {{gli|guanine}} ({{font|G|font=courier|size=big}}) residues will be equal to the number of {{gli|cytosine}} ({{font|C|font=courier|size=big}}) residues; accordingly, the total number of {{gli|glossary=Glossary of genetics (M–Z)|purines}} ({{font|A|font=courier|size=big}} + {{font|G|font=courier|size=big}}) will equal the total number of {{gli|glossary=Glossary of genetics (M–Z)|pyrimidines}} ({{font|T|font=courier|size=big}} + {{font|C|font=courier|size=big}}). These observations illustrate the highly specific nature of the {{gli|complementary}} {{gli|base pair|base-pairing}} that occurs in all {{gli|duplex}} DNA molecules: even though non-standard pairings are technically possible, they are exceptionally rare because the standard ones are strongly favored in most conditions. Still, the 1:1 equivalence is seldom exact, since at any given time nucleobase ratios are inevitably distorted to some small degree by {{gli|DNA repair|unrepaired}} {{gli|glossary=Glossary of genetics (M–Z)|mismatch|mismatches}}, missing bases, and non-canonical bases. The presence of {{gli|glossary=Glossary of genetics (M–Z)|ssDNA|single-stranded DNA}} polymers also alters the proportions, as the sequence of an individual {{gli|glossary=Glossary of genetics (M–Z)|strand}} may contain any number of any of the bases.}}

{{term|charged tRNA}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|tRNA|transfer RNA}} to which an {{gli|amino acid}} has been attached; i.e. an {{gli|aa-tRNA|aminoacylated tRNA}}. {{gli|glossary=Glossary of genetics (M–Z)|uncharged tRNA|Uncharged tRNAs}} lack amino acids.<ref name="DoG7"/>}}

{{term|chDNA}}
{{defn|See ''{{gli|chloroplast DNA}}''.}}

{{term|[[Biology:Chemiosmosis|chemiosmosis]]}}
{{defn|}}

{{term|[[Philosophy:Chemokinesis|chemokinesis]]}}
{{defn|}}

{{term|[[Physics:Chemotaxis|chemotaxis]]}}
{{defn|}}

{{term|[[Biology:Chiasma (genetics)|chiasma]]}}{{anchor|chiasmata}}
{{ghat|Plural '''chiasmata'''.}}
{{defn|A cross-shaped junction that forms the physical point of contact between two non-sister {{gli|chromatids}} belonging to {{gli|homologous chromosomes}} during {{gli|glossary=Glossary of genetics (M–Z)|synapsis}}. As well as ensuring proper {{gli|glossary=Glossary of genetics (M–Z)|segregation}} of the chromosomes, these junctions are also the {{gli|breakpoints}} at which {{gli|chromosomal crossover}} may occur during {{gli|glossary=Glossary of genetics (M–Z)|mitosis}} or {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}, which results in the reciprocal exchange of DNA between the synapsed chromatids.}}

{{term|[[Biology:Chimera (genetics)|chimerism]]}}
{{defn|The presence of two or more populations of cells with distinct {{gli|genotypes}} in an individual organism, known as a ''chimera'', which has developed from the fusion of cells originating from separate {{gli|glossary=Glossary of genetics (M–Z)|zygotes}}; each population of cells retains its own genome, such that the organism as a whole is a mixture of genetically non-identical tissues. Genetic chimerism may be inherited (e.g. by the fusion of multiple embryos during pregnancy) or acquired after birth (e.g. by allogeneic transplantation of cells, tissues, or organs from a genetically non-identical donor); in plants, it can result from [[Earth:Grafting|grafting]] or errors in cell division. It is similar to but distinct from {{gli|glossary=Glossary of genetics (M–Z)|mosaicism}}.}}

{{term|[[Biology:Chloroplast|chloroplast]]}}{{anchor|chloroplasts}}
{{defn|}}

<span id="cpDNA"></span>{{term|[[Biology:Chloroplast DNA|chloroplast DNA]] (cpDNA, chDNA, ctDNA)}}
{{defn|The set of {{gli|DNA}} molecules contained within [[Biology:Chloroplast|chloroplast]]s, a type of photosynthetic [[Biology:Plastid|plastid]] [[Biology:Organelle|organelle]] located within the cells of some eukaryotes such as plants and algae, representing a semi-autonomous {{gli|genome}} separate from that within the cell's nucleus. Like other types of plastid DNA, cpDNA usually exists in the form of small circular {{gli|glossary=Glossary of genetics (M–Z)|plasmids}}.}}

{{term|chondriome}}
{{defn|The complete set of [[Biology:Mitochondria|mitochondria]] or of {{gli|glossary=Glossary of genetics (M–Z)|mitochondrial DNA}} within a cell, tissue, organism, or species.}}

{{term|[[Biology:Chromatid|chromatid]]}}{{anchor|chromatids}}
{{defn|One copy of a newly copied {{gli|chromosome}}, which is joined to the original chromosome by a {{gli|centromere}}.}}

{{term|[[Biology:Chromatin|chromatin]]}}
{{defn|A complex of {{gli|DNA}}, {{gli|glossary=Glossary of genetics (M–Z)|RNA}}, and [[Biology:Protein|protein]] found in [[Biology:Eukaryote|eukaryotic]] cells that is the primary substance comprising {{gli|chromosomes}}. Chromatin functions as a means of {{gli|DNA condensation|packaging}} very long DNA molecules into highly organized and densely compacted shapes, which prevents the strands from becoming tangled, reinforces the DNA during cell division, helps to prevent DNA damage, and plays an important role in regulating {{gli|gene expression}} and {{gli|DNA replication}}.}}

<span id="ChIP"></span>{{term|[[Biology:Chromatin immunoprecipitation|chromatin immunoprecipitation]] (ChIP)}}
{{defn|}}

{{term|chromocenter}}
{{defn|A central amorphous mass of {{gli|glossary=Glossary of genetics (M–Z)|polytene chromosomes}} found in the nuclei of cells of the salivary glands in ''[[Biology:Drosophila|Drosophila]]'' larvae and resulting from the fusion of {{gli|heterochromatic}} regions surrounding the {{gli|centromeres}} of the somatically paired chromosomes, with the distal {{gli|euchromatic}} arms radiating outward.<ref name="DoG7"/>}}

{{term|[[Biology:Chromomere|chromomere]]}}
{{ghat|Also '''idiomere'''.}}
{{defn|A region of a {{gli|chromosome}} that has been locally compacted or {{gli|glossary=Glossary of genetics (M–Z)|supercoiling|coiled}} into {{gli|chromatin}}, conspicuous under a microscope as a "bead", node, or dark-staining band, especially when contrasted with nearby uncompacted strings of DNA.}}

{{term|[[Biology:Chromosomal crossover|chromosomal crossover]]}}{{anchor|chromosomal crossovers|crossover|crossovers}}
{{ghat|Also '''crossing over'''.}}
{{defn|}}

{{term|chromosomal DNA}}
{{defn|{{gli|DNA}} contained in {{gli|chromosomes}}, as opposed to {{gli|extrachromosomal DNA}}. The term is generally used synonymously with {{gli|genomic DNA}}.}}

{{term|chromosomal duplication}}
{{defn|The {{gli|duplication}} of an entire {{gli|chromosome}}, as opposed to a segment of a chromosome or an {{gli|gene duplication|individual gene}}.}}

{{term|[[Biology:Chromosome|chromosome]]}}{{anchor|chromosomes|chromosomal}}
{{defn|A {{gli|nucleus|nuclear}} {{gli|DNA}} molecule containing part or all of the genetic material of an organism. Chromosomes may be considered a sort of molecular "package" for carrying DNA within the {{gli|glossary=Glossary of genetics (M–Z)|nucleus}} of cells and, in most [[Biology:Eukaryote|eukaryote]]s, are composed of long strands of DNA coiled with {{gli|histone|packaging proteins}} which bind to and {{gli|DNA condensation|condense}} the strands to prevent them from becoming an unmanageable tangle. Chromosomes are most easily distinguished and studied in their completely condensed forms, which only occur during {{gli|glossary=Glossary of genetics (M–Z)|mitosis|cell division}}. Some simple organisms have only one chromosome made of circular DNA, while most eukaryotes have multiple chromosomes made of linear DNA.}}

{{term|chromosome condensation}}
{{defn|The process by which eukaryotic chromosomes become shorter, thicker, denser, and more conspicuous under a microscope during {{gli|glossary=Glossary of genetics (M–Z)|prophase}} due to systemic coiling and {{gli|glossary=Glossary of genetics (M–Z)|supercoiling}} of {{gli|chromatin|chromatic}} strands of DNA in preparation for [[Biology:Cell division|cell division]].}}

{{term|[[Biology:Chromosome segregation|chromosome segregation]]}}
{{anchor|segregation|segregate|segregates|segregating|segregated}}
{{defn|The process by which {{gli|glossary=Glossary of genetics (M–Z)|sister chromatids}} or {{gli|glossary=Glossary of genetics (M–Z)|synapsis|paired}} {{gli|homologous chromosomes}} separate from each other and migrate to opposite sides of the dividing cell during {{gli|glossary=Glossary of genetics (M–Z)|mitosis}} or {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}.}}

{{term|chromosome walking}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|primer walking}}''.}}

{{term|[[Biology:Cilium|cilium]]}}{{anchor|cilia}}
{{ghat|(pl.) '''cilia'''}}
{{defn|A slender, thread-like, {{gli|glossary=Glossary of cellular and molecular biology (M–Z)|membrane-bound organelle|membrane-bound}} projection, longer than a {{gli|glossary=Glossary of cellular and molecular biology (M–Z)|microvillus}} but shorter than a {{gli|flagellum}}, extending from the surface of a eukaryotic cell. Most eukaryotic cells have at least one ''primary cilium'' which serves in a sensory or signaling capacity; some cells employ thousands of ''motile cilia'' covering their entire surface as a way of moving extracellular material past the cell or of moving the cell itself.}}

{{term|circular DNA}}
{{defn|Any {{gli|DNA}} molecule, {{gli|glossary=Glossary of genetics (M–Z)|ssDNA|single-stranded}} or {{gli|dsDNA|double-stranded}}, which forms a continuous closed loop without ends; e.g. [[Biology:Circular chromosome|bacterial chromosomes]], {{gli|glossary=Glossary of genetics (M–Z)|mtDNA|mitochondrial}} and {{gli|glossary=Glossary of genetics (M–Z)|plastid|plastid DNA}}, as well as many other varieties of {{gli|extrachromosomal DNA}}, including {{gli|glossary=Glossary of genetics (M–Z)|plasmids}} and some viral DNA. Contrast ''{{gli|linear DNA}}''.}}

<span id="ctDNA"></span>{{term|[[Biology:Circulating tumor DNA|circulating tumor DNA]] (ctDNA)}}
{{defn|Any {{gli|cfDNA|extracellular DNA}} fragments derived from tumor cells which are circulating freely in the bloodstream.}}

{{term|''cis''}}
{{defn|On the same side; adjacent to; {{gli|cis-acting|acting}} from the same molecule. Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|trans}}''.}}

{{term|''cis''-acting}}
{{defn|Affecting a {{gli|gene}} or sequence on the same nucleic acid molecule. A {{gli|locus}} or sequence within a particular DNA molecule such as a {{gli|chromosome}} is said to be ''cis''-acting if it influences or acts upon other sequences located within short distances (i.e. physically nearby, usually but not necessarily {{gli|downstream}}) on the same molecule or chromosome; or, in the broadest sense, if it influences or acts upon other sequences located anywhere (not necessarily within a short distance) on the same chromosome of a {{gli|homologous chromosomes|homologous pair}}. ''Cis''-acting factors are often involved in the {{gli|gene regulation|regulation}} of {{gli|gene expression}} by acting to inhibit or to facilitate {{gli|glossary=Glossary of genetics (M–Z)|transcription}}. Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|trans-acting}}''.}}

{{term|''cis''-dominant mutation}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|mutation}} occurring within a {{gli|cis-regulatory element|''cis''-regulatory element}} (such as an {{gli|glossary=Glossary of genetics (M–Z)|operator}}) which alters the functioning of a nearby {{gli|gene}} or genes on the same {{gli|chromosome}}. ''Cis''-dominant mutations affect the {{gli|expression}} of genes because they occur at sites that control transcription rather than within the genes themselves.}}

{{term|[[Biology:Cisgenesis|cisgenesis]]}}
{{defn|}}

<span id="cis-regulatory element"></span>{{term|[[Biology:Cis-regulatory element|''cis''-regulatory element]] (CRE)}}
{{ghat|Also '''''cis''-regulatory module (CRM)'''.}}
{{defn|Any sequence or region of {{gli|glossary=Glossary of genetics (M–Z)|ncDNA|non-coding DNA}} which {{gli|regulates}} the {{gli|glossary=Glossary of genetics (M–Z)|transcription}} of nearby {{gli|genes}} (e.g. a {{gli|glossary=Glossary of genetics (M–Z)|promoter}}, {{gli|glossary=Glossary of genetics (M–Z)|operator}}, {{gli|glossary=Glossary of genetics (M–Z)|silencer}}, or {{gli|enhancer}}), typically by serving as a binding site for one or more {{gli|glossary=Glossary of genetics (M–Z)|transcription factors}}. Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|trans-regulatory}}''.}}

{{term|[[Biology:Cisterna|cisterna]]}}
{{ghat|(pl.) '''cisternae'''}}
{{defn|Any of a class of flattened, membrane-bound {{gli|glossary=Glossary of genetics (M–Z)|vesicles}} or {{gli|glossary=Glossary of genetics (M–Z)|saccules}} of the {{gli|glossary=Glossary of genetics (M–Z)|smooth ER|smooth}} and {{gli|glossary=Glossary of genetics (M–Z)|rough ER|rough}} {{gli|endoplasmic reticulum}} and the {{gli|Golgi apparatus}}. By traveling through one or more cisternae, each of which contains a distinct set of enzymes, newly created proteins and polysaccharides undergo chemical modifications such as {{gli|glossary=Glossary of genetics (M–Z)|phosphorylation}} and {{gli|glycosylation}}, which are used as packaging signals to direct their transport to specific destinations within the cell.<ref>{{cite journal |last1=Connerly |first1=P. L. |title=How Do Proteins Move Through the Golgi Apparatus? |journal=Nature Education |date=2010 |volume=3 |issue=9 |page=60 |url=https://www.nature.com/scitable/topicpage/how-do-proteins-move-through-the-golgi-14397318/#:~:text=The%20Golgi%20processes%20proteins%20made,the%20cell%20(trans%20side).}}</ref>}}

{{term|[[Biology:Cistron|cistron]]}}{{anchor|cistrons|cistronic}}
{{defn|}}

{{term|[[Biology:Citric acid cycle|citric acid cycle]]}}
{{defn|}}

{{term|[[Biology:Classical genetics|classical genetics]]}}
{{defn|The branch of {{gli|genetics}} based solely on observation of the visible results of reproductive acts, as opposed to that made possible by the modern techniques and methodologies of [[Biology:Molecular biology|molecular biology]]. Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|molecular genetics}}''.}}

{{term|cleavage}}{{anchor|cleave|cleaves|cleaved|cleaving}}
{{defn|}}

{{term|[[Biology:Cleavage furrow|cleavage furrow]]}}
{{defn|}}

{{term|[[Biology:Clonal selection|clonal selection]]}}
{{defn|}}

{{term|[[Biology:Cloning|cloning]]}}
{{defn|The process of producing, either naturally or artificially, individual organisms or cells which are genetically identical to each other. Clones are the result of all forms of asexual reproduction, and cells that undergo {{gli|glossary=Glossary of genetics (M–Z)|mitosis}} produce daughter cells that are clones of the parent cell and of each other. Cloning may also refer to biotechnology methods which artificially create copies of organisms or cells, or, in {{gli|glossary=Glossary of genetics (M–Z)|molecular cloning}}, copies of DNA fragments or other molecules.}}

{{term|closed chromatin}}
{{defn|See ''{{gli|heterochromatin}}''.}}

{{term|[[Biology:Coactivator (genetics)|coactivator]]}}
{{defn|A type of {{gli|coregulator}} that increases the {{gli|expression}} of one or more genes by binding to an {{gli|activator}}.}}

{{term|[[Biology:Coding strand|coding strand]]}}
{{ghat|Also '''sense strand''', '''positive (+) sense strand''', and '''nontemplate strand'''.}}
{{defn|The strand of a double-stranded DNA molecule whose nucleotide sequence corresponds directly to that of the RNA transcript produced during {{gli|glossary=Glossary of genetics (M–Z)|transcription}} (except that {{gli|glossary=Glossary of genetics (M–Z)|thymine}} bases are substituted with {{gli|glossary=Glossary of genetics (M–Z)|uracil}} bases in the RNA molecule). Though it is not itself transcribed, the coding strand is by convention the strand used when displaying a DNA sequence because of the direct analogy between its sequence and the {{gli|codons}} of the RNA product. Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|template strand}}''; see also ''{{gli|glossary=Glossary of genetics (M–Z)|sense}}''.}}

{{term|codon}}{{anchor|codons}}
{{defn|A series of three consecutive {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} in a coding region of a {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} sequence. Each of these triplets codes for a particular {{gli|amino acid}} or {{gli|glossary=Glossary of genetics (M–Z)|stop codon|stop signal}} during {{gli|glossary=Glossary of genetics (M–Z)|translation|protein synthesis}}. {{gli|DNA}} and {{gli|glossary=Glossary of genetics (M–Z)|RNA}} molecules are each written in a language using four "letters" (four different {{gli|glossary=Glossary of genetics (M–Z)|nucleobase|nucleobases}}), but the language used to construct proteins includes 20 "letters" (20 different amino acids). Codons provide the key that allows these two languages to be {{gli|glossary=Glossary of genetics (M–Z)|translated}} into each other. In general, each codon corresponds to a single amino acid (or stop signal). The full set of codons is called the {{gli|genetic code}}.}}

{{term|[[Biology:Codon usage bias|codon usage bias]]}}
{{defn|The preferential use of a particular {{gli|codon}} to code for a particular {{gli|amino acid}} rather than alternative codons that are synonymous for the same amino acid, as evidenced by differences between organisms in the frequencies of the synonymous codons occurring in their coding DNA. Because the {{gli|genetic code}} is {{gli|degeneracy|degenerate}}, most amino acids can be specified by multiple codons. Nevertheless, certain codons tend to be overrepresented (and others underrepresented) in different species.}}

{{term|[[Biology:Coenocyte|coenocyte]]}}
{{defn|A {{gli|multinucleate}} mass of {{gli|cytoplasm}} bounded by a {{gli|cell wall}} and resulting from continuous cytoplasmic growth and repeated nuclear division without {{gli|cytokinesis}}, found in some species of algae and fungi, e.g. ''[[Biology:Vaucheria|Vaucheria]]'' and ''[[Biology:Physarum|Physarum]]''.<ref name="MacLean">{{cite book |last1=MacLean |first1=Norman |title=Dictionary of Genetics & Cell Biology |date=1987 |publisher=New York University Press |location=New York |isbn=0-8147-5438-4 |url=https://openlibrary.org/works/OL4375066W/Dictionary_of_genetics_cell_biology?edition=key%3A/books/OL2398237M}}</ref>}}

<span id="coenzyme A"></span>{{term|[[Chemistry:Coenzyme A|coenzyme A]] (CoA)}}
{{defn|}}

{{term|[[Biology:Cofactor (biochemistry)|cofactor]]}}{{anchor|cofactors}}
{{defn|Any non-protein organic compound that is bound to an [[Biology:Enzyme|enzyme]]. Cofactors are required for the initiation of [[Chemistry:Catalysis|catalysis]].}}

<span id="comparative genomic hybridization"></span>{{term|[[Biology:Comparative genomic hybridization|comparative genomic hybridization]] (CGH)}}
{{defn|}}

{{term|[[Biology:Complementarity (molecular biology)|complementarity]]}}{{anchor|complementary|complement|complements}}
{{defn|A property of {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} [[Biology:Biopolymer|biopolymer]]s whereby two polymeric chains or "{{gli|glossary=Glossary of genetics (M–Z)|strands}}" aligned {{gli|antiparallel}} to each other will tend to form {{gli|base pair|base pairs}} consisting of [[Chemistry:Hydrogen bond|hydrogen bond]]s between the individual {{gli|glossary=Glossary of genetics (M–Z)|nucleobases}} comprising each chain, with each type of nucleobase pairing almost exclusively with one other type of nucleobase; e.g. in {{gli|dsDNA|double-stranded}} {{gli|DNA}} molecules, {{font|{{gli|adenine|A}}|font=courier|size=big}} pairs only with {{font|{{gli|glossary=Glossary of genetics (M–Z)|thymine|T}}|font=courier|size=big}} and {{font|{{gli|cytosine|C}}|font=courier|size=big}} pairs only with {{font|{{gli|guanine|G}}|font=courier|size=big}}. Strands that are paired in such a way, and the bases themselves, are said to be ''complementary''. The degree of complementarity between two strands strongly influences the stability of the {{gli|duplex}} molecule; certain sequences may also be internally complementary, which can result in a single strand {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid secondary structure|binding to itself}}. Complementarity is fundamental to the mechanisms governing {{gli|DNA replication}}, {{gli|glossary=Glossary of genetics (M–Z)|transcription}}, and {{gli|DNA repair}}.}}

<span id="cDNA"></span>{{term|[[Biology:Complementary DNA|complementary DNA]] (cDNA)}}
{{ghat|Also '''copy DNA'''.}}
{{defn|{{gli|DNA}} that is synthesized from a single-stranded {{gli|glossary=Glossary of genetics (M–Z)|RNA}} template (typically {{gli|glossary=Glossary of genetics (M–Z)|mRNA}} or {{gli|glossary=Glossary of genetics (M–Z)|miRNA}}) in a reaction catalyzed by the enzyme {{gli|glossary=Glossary of genetics (M–Z)|reverse transcriptase}}. cDNA is produced both naturally by [[Biology:Retrovirus|retrovirus]]es and artificially in certain laboratory techniques, particularly {{gli|glossary=Glossary of genetics (M–Z)|molecular cloning}}. In {{gli|bioinformatics}}, the term may also be used to refer to the sequence of an mRNA transcript expressed as its DNA {{gli|coding strand}} counterpart (i.e. with {{gli|glossary=Glossary of genetics (M–Z)|thymine}} replacing {{gli|glossary=Glossary of genetics (M–Z)|uracil}}).}}

{{term|[[Biology:Complementation (genetics)|complementation]]}}
{{defn|}}

{{term|compound X}}
{{defn|See ''{{gli|attached X}}''.}}

{{term|conditional expression}}
{{defn|The controlled, inducible {{gli|expression}} of a {{gli|glossary=Glossary of genetics (M–Z)|transgene}}, either ''{{gli|in vitro}}'' or ''{{gli|in vivo}}''.}}

{{term|congression}}
{{defn|The movement of chromosomes to the {{gli|glossary=Glossary of genetics (M–Z)|spindle equator}} during the {{gli|glossary=Glossary of genetics (M–Z)|prometaphase}} and {{gli|glossary=Glossary of genetics (M–Z)|metaphase}} stages of {{gli|glossary=Glossary of genetics (M–Z)|mitosis}}.<ref name="DoG7"/>}}

{{term|[[Biology:Consensus sequence|consensus sequence]]}}
{{ghat|Also '''canonical sequence'''.}}
{{defn|A calculated order of the most frequent {{gli|glossary=Glossary of genetics (M–Z)|residues}} (of either {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} or {{gli|amino acids}}) found at each position in a common {{gli|glossary=Glossary of genetics (M–Z)|sequence alignment}} and obtained by comparing multiple closely related sequence alignments.}}

{{term|conservative replication}}
{{defn|A hypothetical mode of {{gli|glossary=Glossary of genetics (0–L)|DNA replication}} in which the two parental {{gli|strands}} of the original {{gli|glossary=Glossary of genetics (0–L)|dsDNA|double-stranded DNA}} molecule ultimately remain complemented to each other at the end of the replication process, and the two daughter strands end up forming their own separate molecule; hence one molecule is composed of both of the starting strands while the other is composed entirely of newly synthesized strands. This is in contrast to {{gli|glossary=Glossary of genetics (0–L)|semiconservative replication}}, in which each molecule is a hybrid of one old and one new strand.See also ''{{gli|glossary=Glossary of genetics (0–L)|dispersive replication}}''.}}

{{term|[[Biology:Conserved sequence|conserved sequence]]}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence|nucleic acid}} or {{gli|glossary=Glossary of genetics (M–Z)|protein}} sequence that is highly similar or identical across many species or within a {{gli|genome}}, indicating that it has remained relatively unchanged through a long period of evolutionary time.}}

{{term|conspecific}}
{{defn|Belonging to the same species.}}

{{term|constitutive expression}}
{{defn|no=1|The continuous {{gli|glossary=Glossary of genetics (M–Z)|transcription}} of a {{gli|gene}}, as opposed to {{gli|facultative expression}}, in which a gene is only transcribed as needed. A gene that is transcribed continuously is called a ''constitutive gene''.}}
{{defn|no=2|A gene whose expression depends only on the efficiency of its {{gli|glossary=Glossary of genetics (M–Z)|promoter}} in binding {{gli|glossary=Glossary of genetics (M–Z)|RNA polymerase}},<ref name="DoG7"/> and not on any {{gli|glossary=Glossary of genetics (M–Z)|transcription factors}} or other {{gli|gene regulation|regulatory elements}} which might {{gli|glossary=Glossary of genetics (M–Z)|upregulation|promote}} or {{gli|downregulation|inhibit}} its transcription.}}

{{term|[[Biology:Contact inhibition|contact inhibition]]}}
{{defn|}}

{{term|[[Biology:Contig|contig]]}}
{{defn|A continuous sequence of {{gli|genomic DNA}} generated by assembling cloned fragments by means of their overlapping sequences.<ref name="Lewin"/>}}

{{term|copy DNA (cDNA)}}
{{defn|See ''{{gli|cDNA|complementary DNA}}''.}}

{{term|copy error}}{{anchor|copy errors}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|mutation}} resulting from a mistake made during {{gli|DNA replication}}.<ref name="DoG7"/>}}

<span id="copy-number variation"></span>{{term|[[Biology:Copy-number variation|copy-number variation]] (CNV)}}{{anchor|copy number}}
{{defn|A phenomenon in which sections of a {{gli|genome}} are repeated and the number of {{gli|glossary=Glossary of genetics (M−Z)|repeats}} varies between individuals in the population, usually as a result of {{gli|gene duplication|duplication}} or {{gli|deletion}} events that affect entire genes or sections of chromosomes. Copy-number variations play an important role in generating {{gli|genetic variation}} within a population.}}

{{term|coregulator}}
{{defn|A protein that works together with one or more {{gli|glossary=Glossary of genetics (M–Z)|transcription factors}} to regulate {{gli|gene expression}}.}}

{{term|[[Biology:Corepressor|corepressor]]}}
{{defn|A type of {{gli|coregulator}} that reduces (represses) the {{gli|expression}} of one or more genes by binding to and activating a {{gli|glossary=Glossary of genetics (M–Z)|repressor}}.}}

{{term|[[Biology:Cosmid|cosmid]]}}
{{defn|}}

{{term|cpDNA}}
{{defn|See ''{{gli|cpDNA|chloroplast DNA}}''.}}

{{term|CpG island}}{{anchor|CpG islands}}
{{ghat|Also '''CG island''' and '''C-G island'''.}}
{{defn|A region of a {{gli|genome}} in which {{gli|CpG sites}} occur {{gli|glossary=Glossary of genetics (M–Z)|repeat|repetitively}} or with high frequency.}}

{{term|[[Biology:CpG site|CpG site]]}}{{anchor|CpG sites|CpG|CG|C-G}}
{{ghat|Also '''CG site''' and '''C-G site'''.}}
{{defn|A sequence of DNA in which a {{gli|cytosine}} nucleotide is immediately followed by a {{gli|guanine}} nucleotide on the same {{gli|glossary=Glossary of genetics (M–Z)|strand}} in the 5'-to-3' {{gli|direction}}; the "p" in CpG refers simply to the intervening {{gli|glossary=Glossary of genetics (M–Z)|phosphate}} group linking the two consecutive nucleotides.}}

{{term|[[Biology:CRISPR gene editing|CRISPR gene editing]]}}
{{defn|}}

{{term|crossing over}}
{{defn|See ''{{gli|chromosomal crossover}}''.}}

{{term|[[Biology:Crosslinking of DNA|crosslink]]}}
{{defn|An abnormal chemical bond between two or more {{gli|glossary=Glossary of genetics (M–Z)|nucleobases}} on opposite {{gli|glossary=Glossary of genetics (M–Z)|strands}} of a {{gli|dsDNA|double-stranded DNA}} molecule (''interstrand''), or between bases on the same strand (''intrastrand''), specifically via the formation of [[Chemistry:Covalent bond|covalent bond]]s that are stronger than the hydrogen bonds of {{gli|base pairing}}. Crosslinks can be generated by a variety of exogenous and endogenous agents, and tend to interfere with normal cellular processes such as {{gli|DNA replication}} and {{gli|glossary=Glossary of genetics (M–Z)|transcription}}. They are common targets of {{gli|DNA repair}} pathways.}}

<span id="CUT"></span>{{term|[[Biology:Cryptic unstable transcript|cryptic unstable transcript]] (CUT)}}
{{defn|}}

{{term|ctDNA}}
{{defn|no=1|An abbreviation of {{gli|ctDNA|circulating tumor DNA}}.}}
{{defn|no=2|An abbreviation of {{gli|cpDNA|chloroplast DNA}}.}}

<span id="c-terminus"></span>{{term|[[Biology:C-terminus|C-terminus]]}}{{anchor|C-terminal|c-terminal}}
{{ghat|Also '''carboxyl terminus'''.}}
{{defn|The end of a linear chain of {{gli|amino acids}} (i.e. a {{gli|glossary=Glossary of genetics (M–Z)|peptide}}) that is terminated by the free carboxyl group ({{chem|–COOH}}) of the last amino acid to be added to the chain during {{gli|glossary=Glossary of genetics (M–Z)|translation}}. This amino acid is said to be ''C-terminal''. By convention, sequences, domains, active sites, or any other structure positioned nearer to the C-terminus of the {{gli|glossary=Glossary of genetics (M–Z)|polypeptide}} or the folded {{gli|glossary=Glossary of genetics (M−Z)|protein}} it forms relative to others are described as {{gli|downstream}}. Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|N-terminus}}''.}}

{{term|[[Biology:C-value|C-value]]}}
{{defn|The total amount of {{gli|DNA}} contained within a {{gli|haploid}} {{gli|glossary=Glossary of genetics (M–Z)|nucleus}} (e.g. a {{gli|gamete}}) of a particular organism or species, expressed in number of {{gli|base pairs}} or in units of mass (typically picograms); or, equivalently, one-half the amount in a {{gli|diploid}} {{gli|glossary=Glossary of genetics (M–Z)|somatic cell}}. For simple diploid [[Biology:Eukaryote|eukaryote]]s the term is often used interchangeably with {{gli|genome size}}, but in certain cases, e.g. in hybrid {{gli|glossary=Glossary of genetics (M–Z)|polyploids}} descended from parents of different species, the C-value may actually represent two or more distinct {{gli|genomes}} contained within the same nucleus. C-values apply only to {{gli|genomic DNA}}, and notably exclude {{gli|extrachromosomal DNA|extranuclear DNA}}.}}

{{term|[[Biology:C-value enigma|C-value enigma]]}}
{{ghat|Also '''C-value paradox'''.}}
{{defn|A term used to describe a diverse variety of questions regarding the immense variation in nuclear {{gli|C-value}} or {{gli|genome size}} among eukaryotic species, in particular the observation that genome size does not correlate with the perceived complexity of organisms, nor necessarily with the number of {{gli|genes}} they possess; for example, many single-celled [[Biology:Protist|protist]]s have genomes containing thousands of times more DNA than the [[Biology:Human genome|human genome]]. This was considered paradoxical until the discovery that eukaryotic genomes consist mostly of {{gli|glossary=Glossary of genetics (M–Z)|ncDNA|non-coding DNA}}, which lacks genes entirely. The focus of the enigma has since shifted to understanding why and how genomes came to be filled with so much non-coding DNA, and why some genomes have a higher gene content than others.}}

<span id="cyclic AMP"></span>{{term|[[Chemistry:Cyclic adenosine monophosphate|cyclic adenosine monophosphate]] (cAMP)}}
{{defn|}}

{{term|cyclosis}}
{{defn|See ''{{gli|cytoplasmic streaming}}''.}}

<span id="cytidine"></span>{{term|term=[[Chemistry:Cytidine|cytidine]]|content=[[Chemistry:Cytidine|cytidine]] ({{font|C|font=courier|size=large}}, Cyd)}}
{{defn|One of the four standard {{gli|glossary=Glossary of genetics (M–Z)|nucleosides}} used in {{gli|glossary=Glossary of genetics (M–Z)|RNA}} molecules, consisting of a {{gli|cytosine}} {{gli|base}} with its N<sub>9</sub> nitrogen {{gli|glycosidic bond|bonded}} to the C<sub>1</sub> carbon of a {{gli|glossary=Glossary of genetics (M–Z)|ribose}} sugar. Cytosine bonded to {{gli|deoxyribose}} is known as {{gli|deoxycytidine}}, which is the version used in {{gli|DNA}}.}}

{{term|[[Biology:Cytochemistry|cytochemistry]]}}
{{defn|The branch of cell biology involving the detection and identification of the various structures and components within cells by means of biochemical analysis and visualization, in particular the localization of cellular constituents by using techniques such as chemical {{gli|glossary=Glossary of genetics (M−Z)|staining}} and {{gli|immunostaining}}, [[Physics:Spectrophotometry|spectrophotometry]] and [[Physics:Spectroscopy|spectroscopy]], radioautography, and [[Physics:Electron microscopy|electron microscopy]].}}

{{term|[[Biology:Cytogenetics|cytogenetics]]}}
{{defn|The branch of {{gli|genetics}} that studies how {{gli|chromosomes}} influence and relate to [[Biology:Cell|cell]] behavior and function, particularly during {{gli|glossary=Glossary of genetics (M–Z)|mitosis}} and {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}.}}

{{term|[[Biology:Cytokine|cytokine]]}}
{{defn|}}

{{term|[[Biology:Cytokinesis|cytokinesis]]}}
{{defn|The final stage of {{gli|cell division}} in both {{gli|glossary=Glossary of cellular and molecular biology (M–Z)|mitosis}} and {{gli|glossary=Glossary of cellular and molecular biology (M–Z)|meiosis}}, usually immediately following the division of the {{gli|glossary=Glossary of cellular and molecular biology (M–Z)|nucleus}}, during which the {{gli|cytoplasm}} of the parent cell is {{gli|cleaved}} and divided approximately evenly between two {{gli|daughter cells}}. In animal cells, this process occurs by the closing of a [[Biology:Microfilament|microfilament]] {{gli|contractile ring}} in the equatorial region of the dividing cell. Contrast ''{{gli|karyokinesis}}''.}}

{{term|cytology}}{{anchor|cytological}}
{{defn|The study of the morphology, processes, and life history of living cells, particularly by means of light and electron microscopy.<ref name="MacLean"/> The term is also sometimes used as a synonym for the broader field of {{gli|cell biology}}.}}

{{term|cytolysis}}
{{defn|See ''{{gli|lysis}}''.}}

{{term|cytometer}}
{{defn|}}

{{term|[[Biology:Cytomics|cytomics]]}}
{{defn|The interdisciplinary field that studies {{gli|cell biology}}, {{gli|cytology}}, and {{gli|biochemistry}} at the level of an individual cell by making use of single-cell molecular techniques and advanced microscopy to visualize the interactions of cellular components ''{{gli|in vivo}}''.<ref>{{cite journal|last1=Valet|first1=Günter|title=Cytomics: An entry to biomedical cell systems biology|journal=Cytometry Part A|volume=63A|issue=2|year=2005|pages=67–68|issn=1552-4922|doi=10.1002/cyto.a.20110|pmid=15657925 |doi-access=free}}</ref>}}

{{term|[[Biology:Cytoplasm|cytoplasm]]}}{{anchor|cytoplasmic}}
{{defn|}}

{{term|[[Biology:Cytoplasmic streaming|cytoplasmic streaming]]}}
{{ghat|Also '''protoplasmic streaming''' and '''cyclosis'''.}}
{{defn|The flow of the {{gli|cytoplasm}} inside a cell, driven by forces exerted upon cytoplasmic fluids by the {{gli|cytoskeleton}}. This flow functions partly to speed up the transport of molecules and {{gli|organelles}} suspended in the cytoplasm to different parts of the cell, which would otherwise have to rely on passive [[Physics:Diffusion|diffusion]] for movement. It is most commonly observed in very large eukaryotic cells, for which there is a greater need for transport efficiency.}}

{{term|[[Biology:Cytoplast|cytoplast]]}}{{anchor|cytoplasts}}
{{defn|An {{gli|enucleated}} eukaryotic cell; or all other cellular components besides the nucleus (i.e. the cell membrane, cytoplasm, organelles, etc.) considered collectively. The term is most often used in the context of {{gli|glossary=Glossary of genetics (M–Z)|nuclear transfer}} experiments, during which the cytoplast can sometimes remain viable in the absence of a nucleus for up to 48 hours.<ref name="Rieger"/>}}

<span id="cytosine"></span>{{term|term=[[Chemistry:Cytosine|cytosine]]|content=[[Chemistry:Cytosine|cytosine]] ({{font|C|font=courier|size=large}})}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|pyrimidine}} {{gli|glossary=Glossary of genetics (M–Z)|nucleobase}} used as one of the four standard nucleobases in both {{gli|DNA}} and {{gli|glossary=Glossary of genetics (M–Z)|RNA}} molecules. Cytosine forms a {{gli|base pair}} with {{gli|guanine}}.}}

{{term|[[Biology:Cytosol|cytosol]]}}
{{ghat|Also '''hyaloplasm'''.}}
{{defn|The soluble phase of the {{gli|cytoplasm}}, in which small particles such as {{gli|ribosomes}}, {{gli|proteins}}, {{gli|nucleic acids}}, and many other molecules are suspended or dissolved, excluding larger structures and {{gli|organelles}} such as {{gli|mitochondria}}, {{gli|chloroplasts}}, {{gli|lysosomes}}, and the {{gli|endoplasmic reticulum}}.<ref name="MacLean"/>}}

{{glossary end}}


==D==
{{glossary}}
{{term|[[Biology:De novo mutation|''de novo'' mutation]]}}{{anchor|de novo mutation}}
{{defn|A spontaneous {{gli|glossary=Glossary of genetics (M–Z)|mutation}} in the genome of an individual organism that is new to that organism's lineage, having first appeared in a {{gli|germ cell}} of one of the organism's parents or in the fertilized egg that develops into the organism; i.e. a mutation that was not present in either parent's genome.<ref name="DoG7"/>}}

{{term|[[Biology:De novo synthesis|''de novo'' synthesis]]}}{{anchor|de novo synthesis}}
{{defn|The assembly of a synthetic {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence}} from free {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} without relying on an existing {{gli|glossary=Glossary of genetics (M–Z)|template strand}}, i.e. ''de novo'', by any of a variety of laboratory methods. ''De novo'' synthesis makes it theoretically possible to construct completely {{gli|artificial gene synthesis|artificial molecules}} with no naturally occurring equivalent, and no restrictions on size or sequence. It is performed routinely in the commercial production of customized, made-to-order {{gli|glossary=Glossary of genetics (M–Z)|oligonucleotide}} sequences such as {{gli|glossary=Glossary of genetics (M–Z)|primers}}.}}

{{term|[[Biology:Codon degeneracy|degeneracy]]}}{{anchor|codon degeneracy}}
{{defn|The redundancy of the {{gli|genetic code}}, exhibited as the multiplicity of different {{gli|codons}} that specify the same {{gli|amino acid}}. For example, in the {{gli|glossary=Glossary of genetics (M–Z)|standard genetic code}}, the amino acid [[Chemistry:Serine|serine]] is specified by six unique codons ({{font|UCA|font=courier|size=big}}, {{font|UCG|font=courier|size=big}}, {{font|UCC|font=courier|size=big}}, {{font|UCU|font=courier|size=big}}, {{font|AGU|font=courier|size=big}}, and {{font|AGC|font=courier|size=big}}). Codon degeneracy accounts for the existence of {{gli|glossary=Glossary of genetics (M–Z)|synonymous mutations}}.}}

{{term|[[Biology:Deletion (genetics)|deletion]]}}{{anchor|deletions}}
{{ghat|Denoted in shorthand with the symbol '''''Δ'''''.}}
{{defn|A type of {{gli|glossary=Glossary of genetics (M–Z)|mutation}} in which one or more {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} are removed from a {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence}}.}}

{{term|[[Biology:Denaturation (biochemistry)|denaturation]]}}{{anchor|denature|denatures|denatured|denaturing}}
{{defn|The process by which {{gli|glossary=Glossary of genetics (M–Z)|nucleic acids}} or {{gli|glossary=Glossary of genetics (M–Z)|proteins}} lose their {{gli|glossary=Glossary of genetics (M–Z)|quaternary}}, {{gli|glossary=Glossary of genetics (M–Z)|tertiary}}, and/or {{gli|glossary=Glossary of genetics (M–Z)|secondary structures}}, either reversibly or irreversibly, through the application of some external chemical or mechanical stress, e.g. by heating, agitation, or exposure to a strong acid or base, all of which can disrupt intermolecular forces such as hydrogen bonding and thereby change or destroy chemical activity. Denatured proteins may be both a cause and a consequence of cell death. Denaturation may also be a normal process; the denaturation of {{gli|double-stranded DNA}} molecules, for example, which breaks the hydrogen bonds between {{gli|base pairs}} and causes the separation of the duplex molecule into two {{gli|glossary=Glossary of genetics (M–Z)|single strands}}, is a necessary step in {{gli|DNA replication}} and {{gli|glossary=Glossary of genetics (M–Z)|transcription}} and hence is routinely performed by enzymes such as {{gli|helicases}}. The same mechanism is also fundamental to laboratory methods such as {{gli|glossary=Glossary of genetics (M–Z)|PCR}}.}}

{{term|[[Chemistry:Deoxyadenosine|deoxyadenosine]]}}
{{ghat|Abbreviated in shorthand with ''{{font|dA|font=courier|size=big}}''.}}
{{defn|One of the four standard {{gli|deoxyribonucleosides}} used in {{gli|DNA}} molecules, consisting of an {{gli|adenine}} {{gli|base}} with its N<sub>9</sub> nitrogen {{gli|glycosidic bond|bonded}} to the C<sub>1</sub> carbon of a {{gli|deoxyribose}} sugar. Adenine bonded to {{gli|glossary=Glossary of genetics (M–Z)|ribose}} forms an alternate compound known simply as {{gli|adenosine}}, which is used in {{gli|glossary=Glossary of genetics (M–Z)|RNA}}.}}

{{term|[[Chemistry:Deoxycytidine|deoxycytidine]]}}
{{ghat|Abbreviated in shorthand with ''{{font|dC|font=courier|size=big}}''.}}
{{defn|One of the four standard {{gli|deoxyribonucleosides}} used in {{gli|DNA}} molecules, consisting of a {{gli|cytosine}} {{gli|base}} with its N<sub>9</sub> nitrogen {{gli|glycosidic bond|bonded}} to the C<sub>1</sub> carbon of a {{gli|deoxyribose}} sugar. Cytosine bonded to {{gli|glossary=Glossary of genetics (M–Z)|ribose}} forms an alternate compound known simply as {{gli|cytidine}}, which is used in {{gli|glossary=Glossary of genetics (M–Z)|RNA}}.}}

{{term|[[Chemistry:Deoxyguanosine|deoxyguanosine]]}}
{{ghat|Abbreviated in shorthand with ''{{font|dG|font=courier|size=big}}''.}}
{{defn|One of the four standard {{gli|deoxyribonucleosides}} used in {{gli|DNA}} molecules, consisting of a {{gli|guanine}} {{gli|base}} with its N<sub>9</sub> nitrogen {{gli|glycosidic bond|bonded}} to the C<sub>1</sub> carbon of a {{gli|deoxyribose}} sugar. Guanine bonded to {{gli|glossary=Glossary of genetics (M–Z)|ribose}} forms an alternate compound known simply as {{gli|guanosine}}, which is used in {{gli|glossary=Glossary of genetics (M–Z)|RNA}}.}}

<span id="DNase"></span>{{term|[[Biology:Deoxyribonuclease|deoxyribonuclease]] (DNase)}}
{{defn|Any of a class of {{gli|glossary=Glossary of genetics (M–Z)|nuclease}} enzymes which catalyze the hydrolytic cleavage of {{gli|glossary=Glossary of genetics (M–Z)|phosphodiester bonds}} in {{gli|DNA}} molecules, thereby severing {{gli|glossary=Glossary of genetics (M–Z)|strands}} of {{gli|deoxyribonucleotides}} and causing the degradation of DNA polymers into smaller components. Compare ''{{gli|glossary=Glossary of genetics (M–Z)|ribonuclease}}''.}}

<span id="dNA"></span>{{term|deoxyribonucleic acid (DNA)}}
{{defn|A [[Chemistry:Polymer|polymer]]ic {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} molecule composed of a series of {{gli|deoxyribonucleotides}}, each of which incorporates one of four canonical {{gli|glossary=Glossary of genetics (M–Z)|nucleobases}}: {{gli|adenine}} ({{font|A|font=courier|size=big}}), {{gli|guanine}} ({{font|G|font=courier|size=big}}), {{gli|cytosine}} ({{font|C|font=courier|size=big}}), and {{gli|glossary=Glossary of genetics (M–Z)|thymine}} ({{font|T|font=courier|size=big}}). DNA is most often found in {{gli|dsDNA|double-stranded}} form, which consists of two {{gli|complementary}} {{gli|antiparallel}} nucleotide chains in which each of the nucleobases on each individual {{gli|glossary=Glossary of genetics (M–Z)|strand}} is {{gli|glossary=Glossary of genetics (M–Z)|paired}} via hydrogen bonding with one on the opposite strand; this structure commonly occurs in the shape of a {{gli|double helix}}. DNA can also exist in {{gli|glossary=Glossary of genetics (M–Z)|ssDNA|single-stranded}} form. By storing and encoding genetic information in the {{gli|glossary=Glossary of genetics (M−Z)|sequence}} of its nucleotides, DNA serves as the universal molecular basis of biological inheritance and the fundamental template from which all proteins, cells, and living organisms are constructed.}}

{{term|[[Biology:Deoxyribonucleotide|deoxyribonucleotide]]}}{{anchor|deoxyribonucleotides}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|nucleotide}} containing {{gli|deoxyribose}} as its pentose sugar component, and the monomeric subunit of {{gli|deoxyribonucleic acid}} (DNA) molecules. Deoxyribonucleotides canonically incorporate any of four {{gli|glossary=Glossary of genetics (M–Z)|nitrogenous bases}}: {{gli|adenine}} ({{font|A|font=courier|size=big}}), {{gli|guanine}} ({{font|G|font=courier|size=big}}), {{gli|cytosine}} ({{font|C|font=courier|size=big}}), and {{gli|glossary=Glossary of genetics (M–Z)|thymine}} ({{font|T|font=courier|size=big}}). Compare ''{{gli|glossary=Glossary of genetics (M–Z)|ribonucleotide}}''.}}

{{term|[[Chemistry:Deoxyribose|deoxyribose]]}}
{{ghat|Also '''2-deoxyribose'''.}}
{{defn|A monosaccharide sugar derived from {{gli|glossary=Glossary of genetics (M–Z)|ribose}} by the loss of a single oxygen atom. D-deoxyribose, in its pentose ring form, is one of three primary functional groups of {{gli|deoxyribonucleotides}} and hence of {{gli|DNA|deoxyribonucleic acid}} (DNA) molecules.}}
[[File:The_difference_between_ribose_and_deoxyribose.png|350px|thumb|right|'''{{gli|Deoxyribose}}''' differs from '''{{gli|glossary=Glossary of genetics (M–Z)|ribose}}''' only at the 2' carbon, where ribose has an oxygen atom that deoxyribose lacks (hence its name).]]

{{term|deoxythymidine}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|thymidine}}''.}}

{{term|[[Biology:Dephosphorylation|dephosphorylation]]}}
{{defn|}}

{{term|[[Biology:Desmosome|desmosome]]}}{{anchor|desmosomes}}
{{defn|}}

{{term|destination vector}}
{{defn|}}

{{term|desynapsis}}
{{defn|The failure of {{gli|homologous chromosomes}} that have {{gli|glossary=Glossary of genetics (M–Z)|synapsis|synapsed}} normally during {{gli|glossary=Glossary of genetics (M–Z)|pachynema}} to remain paired during {{gli|diplonema}}. Desynapsis is usually caused by the improper formation of {{gli|chiasmata}}.<ref name="DoG7">{{cite book |last1=King |first1=Robert C. |last2=Stansfield |first2=William D. |last3=Mulligan |first3=Pamela K. |title=A Dictionary of Genetics |date=2006 |publisher=Oxford University Press |location=Oxford |isbn=978-0-19-530762-7 |edition=7th |url=https://openlibrary.org/works/OL2942141W/A_dictionary_of_genetics}}</ref> Contrast ''{{gli|asynapsis}}''.}}

{{term|[[Biology:Developmental biology|developmental biology]]}}
{{defn|}}

{{term|diakinesis}}
{{defn|In {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}, the fifth and final substage of {{gli|glossary=Glossary of genetics (M–Z)|prophase|prophase I}}, following {{gli|diplonema}} and preceding {{gli|glossary=Glossary of genetics (M–Z)|metaphase I}}. During diakinesis, the chromosomes are further condensed, the two {{gli|centrosomes}} reach opposite poles of the cell, and the {{gli|glossary=Glossary of genetics (M–Z)|spindle apparatus}} begins to extend from the poles to the equator.<ref name="DoG7"/>}}

{{term|dicentric}}
{{defn|(of a linear {{gli|chromosome}} or chromosome fragment) Having two {{gli|centromere|centromeres}} instead of the normal one.<ref name="CoG"/>}}

{{term|dinucleotide}}{{anchor|dinucleotides}}
{{defn|Any two {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} which are immediately adjacent to each other on the same {{gli|glossary=Glossary of genetics (M–Z)|strand}} of a {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} molecule.}}

{{term|diploid}}
{{ghat|Denoted in shorthand with the somatic number '''''2n'''''.}}
{{defn|(of a [[Biology:Cell|cell]] or organism) Having two {{gli|homologous chromosomes|homologous}} copies of each {{gli|chromosome}}. Contrast ''{{gli|haploid}}'' and ''{{gli|glossary=Glossary of genetics (M–Z)|polyploid}}''.}}

{{term|diplonema}}
{{ghat|Also '''diplotene stage'''.}}
{{defn|In {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}, the fourth of the five substages of {{gli|glossary=Glossary of genetics (M–Z)|prophase|prophase I}}, following {{gli|glossary=Glossary of genetics (M–Z)|pachynema}} and preceding {{gli|diakinesis}}. During diplonema, the {{gli|glossary=Glossary of genetics (M–Z)|synaptonemal complex}} disassembles and the paired {{gli|homologous chromosomes}} begin to separate from one another, though they remain tightly bound at the {{gli|chiasmata}} where {{gli|crossover}} has occurred.}}

{{term|[[Biology:Direct repeat|direct repeat]]}}{{anchor|direct repeats}}
{{defn|Any two or more {{gli|glossary=Glossary of genetics (M–Z)|repeat|repetitions}} of a specific {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence|sequence of nucleotides}} occurring in the same orientation (i.e. in precisely the same order and not {{gli|inverted repeat|inverted}}) and on the same {{gli|glossary=Glossary of genetics (M–Z)|strand}}, either separated by intervening nucleotides or not. An example is the sequence {{font|'''TACCG'''|font=courier|size=big|color=green}}{{font|nnnnnn|font=courier|size=big}}{{font|'''TACCG'''|font=courier|size=big|color=green}}, in which {{font|'''TACCG'''|font=courier|size=big|color=green}} occurs twice, though separated by six nucleotides that are not part of the repeated sequence. A direct repeat in which the repeats are immediately adjacent to each other is known as a {{gli|glossary=Glossary of genetics (M–Z)|tandem repeat}}.}}

{{term|[[Biology:Directionality (molecular biology)|directionality]]}}{{anchor|direction|directions|5' to 3'|3' to 5'|5'-to-3'|3'-to-5'}}
{{defn|The end-to-end chemical orientation of a single linear {{gli|glossary=Glossary of genetics (M–Z)|strand}} or {{gli|glossary=Glossary of genetics (M–Z)|sequence}} of a {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} polymer or a {{gli|glossary=Glossary of genetics (M–Z)|polypeptide}}. The nomenclature used to indicate nucleic acid directionality is based on the chemical convention of identifying individual carbon atoms in the {{gli|glossary=Glossary of genetics (M–Z)|ribose}} or {{gli|deoxyribose}} sugars of nucleotides, specifically the {{gli|5' carbon}} and {{gli|3' carbon}} of the pentose ring. The sequence of nucleotides in a polymeric chain may be read or interpreted in the 5'-to-3' direction – i.e. starting from the terminal nucleotide in which the 5' carbon is not connected to another nucleotide, and proceeding to the other terminal nucleotide, in which the 3' carbon is not connected to another nucleotide – or in the opposite 3'-to-5' direction. Most types of nucleic acid synthesis, including {{gli|DNA replication}} and {{gli|glossary=Glossary of genetics (M–Z)|transcription}}, work exclusively in the 5'-to-3' direction, because the enzymes involved can only catalyze the addition of free nucleotides to the open 3'-end of the previous nucleotide in the chain. Because of this, the convention when writing any nucleic acid sequence is to present it in the 5'-to-3' direction from left to right. In {{gli|double-stranded}} nucleic acids, the two paired strands must be {{gli|antiparallel|oriented in opposite directions}} in order to {{gli|base-pair}} with each other. Polypeptide directionality is similarly based on labeling the functional groups in {{gli|amino acids}}, specifically the amino group, which forms the {{gli|glossary=Glossary of genetics (M–Z)|N-terminus}}, and the carboxyl group, which forms the {{gli|C-terminus}}; amino acid sequences are assembled in the N-to-C direction during {{gli|glossary=Glossary of genetics (M–Z)|translation}}, and are almost always written in the same direction.}}

{{term|dispersive replication}}
{{defn|}}

{{term|distance measure}}
{{defn|Any quantity used to measure the dissimilarity between the {{gli|gene expression}} levels of different {{gli|genes}}.<ref name="Priness">{{cite journal|last = Priness|first = I.|author2=Maimon, O. |author3=Ben-Gal, I. |title = Evaluation of gene-expression clustering via mutual information distance measure|journal = BMC Bioinformatics|volume = 8|date = 2007|pages = 111|doi = 10.1186/1471-2105-8-111|pmid = 17397530|pmc = 1858704 | doi-access=free }}</ref>}}

{{term|DNA}}
{{defn|See ''{{gli|dNA|deoxyribonucleic acid}}''.}}

<span id="dNA barcoding"></span>{{term|[[Biology:DNA barcoding|DNA barcoding]]}}
{{defn|A method of taxonomic identification in which short DNA sequences from one or more specific genes are isolated from unidentified samples and then {{gli|glossary=Glossary of genetics (M–Z)|sequence alignment|aligned}} with sequences from a {{gli|library|reference library}} in order to uniquely identify the species or other taxon from which the samples originated. The sequences used in the comparison are chosen carefully from genes that are both widely {{gli|conserved sequence|conserved}} and that show greater {{gli|genetic variation|variation}} between species than within species, e.g. the [[Biology:Cytochrome c oxidase|cytochrome c oxidase]] gene for eukaryotes or certain {{gli|glossary=Glossary of genetics (M–Z)|rRNA|ribosomal RNA}} genes for prokaryotes. These genes are present in nearly all living organisms but tend to evolve different mutations in different species, such that a unique sequence variant can be linked to one particular species, effectively creating a unique identifier akin to a retail [[Barcode|barcode]]. DNA barcoding allows unknown specimens to be identified from otherwise indistinct tissues or body parts, where identification by morphology would be difficult or impossible, and the library of organismal barcodes is now comprehensive enough that even organisms previously unknown to science can often be {{gli|glossary=Glossary of genetics (M–Z)|phylogenetics|phylogenetically}} classified with confidence. The simultaneous identification of multiple different species from a mixed sample is known as ''metabarcoding''.}}

<span id="dNA condensation"></span>{{term|[[Biology:DNA condensation|DNA condensation]]}}
{{defn|The process of compacting very long {{gli|DNA}} molecules into densely packed, orderly configurations such as {{gli|chromosomes}}, either ''{{gli|in vivo}}'' or ''{{gli|in vitro}}''.}}

<span id="dNA fingerprinting"></span>{{term|DNA fingerprinting}}
{{defn|}}

<span id="dNA methylation"></span>{{term|[[Biology:DNA methylation|DNA methylation]]}}
{{defn|}}

<span id="dNA microarray"></span>{{term|[[Biology:DNA microarray|DNA microarray]]}}
{{defn|A {{gli|high-throughput}} technology used to measure {{gli|expression}} levels of {{gli|glossary=Glossary of genetics (M–Z)|mRNA}} transcripts or to detect certain changes in {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence|nucleotide sequence}}. It consists of an array of thousands of microscopic spots of {{gli|DNA}} {{gli|glossary=Glossary of genetics (M–Z)|oligonucleotides}}, called ''features'', each containing picomoles of a specific DNA sequence. This can be a short section of a {{gli|gene}} or any other DNA element, and is used as a {{gli|glossary=Glossary of genetics (M–Z)|probe}} to hybridize a {{gli|cDNA}}, cRNA or {{gli|genomic DNA}} sample (called a ''target'') under {{gli|glossary=Glossary of genetics (M–Z)|stringency|high-stringency}} conditions. Probe-target {{gli|hybridization}} is usually detected and quantified by fluorescence-based detection of {{gli|labelling|fluorophore-labeled}} targets.}}

<span id="dNA polymerase"></span>{{term|[[Biology:DNA polymerase|DNA polymerase]]}}
{{defn|Any of a class of [[Biology:Enzyme|enzyme]]s that synthesizes {{gli|DNA}} molecules from individual {{gli|deoxyribonucleotides}}. DNA polymerases are essential for {{gli|DNA replication}} and usually work in pairs to create identical copies of the two {{gli|glossary=Glossary of genetics (M–Z)|strands}} of an original double-stranded molecule. They build long chains of DNA by adding nucleotides one at a time to the {{gli|3'-end}} of a DNA strand, usually relying on the {{gli|glossary=Glossary of genetics (M–Z)|template strand|template}} provided by the {{gli|complementary}} strand to copy the nucleotide sequence faithfully.}}

<span id="dNA repair"></span>{{term|[[Biology:DNA repair|DNA repair]]}}
{{defn|The set of processes by which a cell identifies and corrects structural damage or {{gli|glossary=Glossary of genetics (M–Z)|mutations}} in the {{gli|DNA}} molecules that encode its {{gli|genome}}. The ability of a cell to repair its DNA is vital to the integrity of the genome and the normal functionality of the organism.}}

<span id="dNA replication"></span>{{term|[[Biology:DNA replication|DNA replication]]}}
{{defn|The process by which a {{gli|DNA}} molecule copies itself, producing two identical copies of one original DNA molecule.}}
[[File:Eukaryotic_DNA_replication.svg|350px|thumb|right|A diagram of the many components of '''{{gli|DNA replication}}''']]

<span id="dNA sequencing"></span>{{term|[[Biology:DNA sequencing|DNA sequencing]]}}{{anchor|sequencing}}
{{defn|The process of determining, by any of a variety of different methods and technologies, the order of the {{gli|bases}} in the long chain of nucleotides that constitutes a {{gli|glossary=Glossary of genetics (M–Z)|sequence}} of {{gli|DNA}}.}}

<span id="dNA turnover"></span>{{term|DNA turnover}}
{{defn|Any mechanism by which {{gli|DNA}} {{gli|glossary=Glossary of genetics (M–Z)|sequences}} are exchanged non-reciprocally (e.g. via {{gli|gene conversion}}, {{gli|glossary=Glossary of genetics (M–Z)|transposition}}, or {{gli|glossary=Glossary of genetics (M–Z)|unequal crossing-over}}) that causes continual fluctuations in the {{gli|copy number}} of DNA {{gli|glossary=Glossary of genetics (M–Z)|motifs}} during an organism's lifetime. Such mechanisms are often major drivers of [[Biology:Speciation|speciation]] between populations.<ref name="Rieger">{{cite book |last1=Rieger |first1=Rigomar |title=Glossary of Genetics: Classical and Molecular |date=1991 |publisher=Springer-Verlag |location=Berlin |isbn=3540520546 |edition=5th |url=https://openlibrary.org/works/OL4093818W/Glossary_of_genetics?edition=glossaryofgeneti0000rieg}}</ref>}}

<span id="DNA-binding domain"></span>{{term|[[Biology:DNA-binding domain|DNA-binding domain]] (DBD)}}
{{defn|}}

<span id="DNA-binding protein"></span>{{term|[[Biology:DNA-binding protein|DNA-binding protein]] (DBP)}}
{{defn|Any {{gli|glossary=Glossary of genetics (M–Z)|polypeptide}} or {{gli|glossary=Glossary of genetics (M–Z)|protein}} containing one or more {{gli|DNA-binding domain|domains}} capable of interacting chemically with one or more parts of a {{gli|DNA}} molecule, and consequently having a specific or general affinity for {{gli|glossary=Glossary of genetics (M–Z)|ssDNA|single-}} and/or {{gli|dsDNA|double-stranded DNA}}. DNA-binding activity often depends on the presence and physical accessibility of a specific nucleobase sequence, and mostly occurs at the {{gli|glossary=Glossary of genetics (M–Z)|major groove}}, since it exposes more of the functional groups that uniquely identify the bases. Binding is also influenced by the spatial conformation of the DNA chain and the occupancy of other proteins near the binding site; many proteins cannot bind to DNA without first undergoing structural changes induced by interactions with other molecules.}}

{{term|DNase}}
{{defn|See ''{{gli|deoxyribonuclease}}''.}}

{{term|donor vector}}
{{defn|}}

{{term|[[Biology:Dosage compensation|dosage compensation]]}}
{{defn|Any mechanism by which organisms neutralize the large difference in {{gli|gene dosage}} caused by the presence of differing numbers of {{gli|glossary=Glossary of genetics (M–Z)|sex chromosomes}} in the different sexes, thereby equalizing the {{gli|expression}} of sex-linked genes so that the members of each sex receive the same or similar amounts of the {{gli|gene product|products}} of such genes. An example is {{gli|glossary=Glossary of genetics (M–Z)|X-inactivation}} in female mammals.}}

{{term|double helix}}
{{defn|The shape most commonly assumed by {{gli|dsDNA|double-stranded}} {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} molecules, resembling a ladder that has been twisted upon its long axis, with the rungs of the ladder consisting of {{gli|glossary=Glossary of genetics (M–Z)|paired}} {{gli|glossary=Glossary of genetics (M–Z)|nucleobases}}. This {{gli|glossary=Glossary of genetics (M–Z)|secondary structure}} is the most energetically stable conformation of the double-stranded forms of both {{gli|DNA}} and {{gli|glossary=Glossary of genetics (M–Z)|RNA}} under most naturally occurring conditions, arising as a consequence of the {{gli|glossary=Glossary of genetics (M–Z)|primary structure}} of the {{gli|glossary=Glossary of genetics (M–Z)|phosphodiester backbone}} and the stacking of the {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} bonded to it. In {{gli|B-DNA}}, the most common DNA variant found in nature, the double helix has a right-handed twist with about 10 base pairs per full turn, and the molecular geometry results in an alternating pattern of "grooves" of differing widths (a {{gli|glossary=Glossary of genetics (M–Z)|major groove}} and a {{gli|glossary=Glossary of genetics (M–Z)|minor groove}}) between the parallel backbones.}}
[[File:DNA orbit animated.gif|thumb|right|Double-stranded DNA most commonly exists in the shape of a '''{{gli|double helix}}'''.]]

<span id="double-strand break"></span>{{term|double-strand break (DSB)}}{{anchor|double-strand breaks}}
{{defn|The loss of continuity of the {{gli|glossary=Glossary of genetics (M–Z)|phosphate backbone|phosphate-sugar backbone}} in both strands of a {{gli|double-stranded DNA}} molecule, in particular when the two breaks occur at sites that are directly across from or very close to each other on the complementary strands.<ref name="Rieger"/> Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|single-strand break}}''.}}

{{term|double-stranded}}{{anchor|duplex}}
{{defn|Composed of two {{gli|antiparallel}}, {{gli|complementary}} {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} molecules or {{gli|glossary=Glossary of genetics (M–Z)|strands}} (either {{gli|dsDNA|DNA–DNA}}, {{gli|dsRNA|RNA–RNA}}, or a {{gli|DNA–RNA hybrid}}) which are held together by [[Chemistry:Hydrogen bond|hydrogen bond]]s between the complementary {{gli|glossary=Glossary of genetics (M–Z)|nucleobases}} of each strand, known as {{gli|base pairing}}. Compare ''{{gli|glossary=Glossary of genetics (M–Z)|single-stranded}}''.}}

{{term|double-stranded DNA (dsDNA)}}{{anchor|dsRNA}}
{{defn|Any {{gli|DNA}} molecule that is composed of two {{gli|antiparallel}}, {{gli|complementary}} {{gli|deoxyribonucleotide}} polymers, known as {{gli|glossary=Glossary of genetics (M–Z)|strands}}, which are bonded together by [[Chemistry:Hydrogen bond|hydrogen bond]]s between the complementary {{gli|glossary=Glossary of genetics (M–Z)|nucleobases}}. Though it is possible for DNA to exist as a {{gli|glossary=Glossary of genetics (M–Z)|ssDNA|single strand}}, it is generally more stable and more common in double-stranded form. In most cases, the complementary {{gli|base pairing}} causes the twin strands to coil around each other in the shape of a {{gli|double helix}}.}}

{{term|double-stranded RNA (dsRNA)}}{{anchor|dsRNA}}
{{defn|Any {{gli|glossary=Glossary of genetics (M–Z)|RNA}} molecule that is composed of two {{gli|antiparallel}}, {{gli|complementary}} {{gli|glossary=Glossary of genetics (M–Z)|ribonucleotide}} polymers, known as {{gli|glossary=Glossary of genetics (M–Z)|strands}}, which are bonded together by [[Chemistry:Hydrogen bond|hydrogen bond]]s between the complementary {{gli|glossary=Glossary of genetics (M–Z)|nucleobases}}. Though RNA usually occurs in {{gli|glossary=Glossary of genetics (M–Z)|ssRNA|single-stranded form}}, it is also capable of forming duplexes in the {{gli|dsDNA|same way as DNA}}; an example is an {{gli|glossary=Glossary of genetics (M–Z)|mRNA}} transcript pairing with an {{gli|asRNA|antisense version}} of the same transcript, which effectively {{gli|gene silencing|silences}} the gene from which the mRNA was transcribed by preventing translation. As in dsDNA, the {{gli|base pairing}} in dsRNA usually causes the twin strands to coil around each other in the shape of a {{gli|double helix}}.}}

{{term|downregulation}}
{{ghat|Also '''repression''' or '''suppression'''.}}
{{defn|Any process, natural or artificial, which decreases the level of {{gli|gene expression}} of a certain {{gli|gene}}. A gene which is observed to be expressed at relatively low levels (such as by detecting lower levels of its {{gli|glossary=Glossary of genetics (M–Z)|mRNA}} transcripts) in one sample compared to another sample is said to be ''downregulated''. Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|upregulation}}''.}}

{{term|downstream}}
{{defn|Towards or closer to the {{gli|3'-end}} of a chain of nucleotides, or to the {{gli|C-terminus}} of a {{gli|glossary=Glossary of genetics (M–Z)|peptide}} chain. Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|upstream}}''.}}

{{term|dsDNA}}
{{defn|See ''{{gli|dsDNA|double-stranded DNA}}''.}}

{{term|dsRNA}}
{{defn|See ''{{gli|dsRNA|double-stranded RNA}}''.}}

{{term|duplex}}
{{defn|See ''{{gli|double-stranded}}''.}}

{{term|duplication}}
{{defn|The production of a second copy of part or all of a {{gli|glossary=Glossary of genetics (M–Z)|nucleotide sequence}} or {{gli|amino acid sequence}}, either naturally or artificially, and the retention of both copies; especially when both the copy and the original sequence are retained ''{{gli|in situ}}'' within the same molecule, often but not necessarily {{gli|glossary=Glossary of genetics (M–Z)|tandem|adjacent}} to each other. See also ''{{gli|gene duplication}}'', ''{{gli|chromosomal duplication}}'', and ''{{gli|glossary=Glossary of genetics (M–Z)|repeat}}''.}}

{{term|dyad}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|sister chromatids}}''.}}

{{glossary end}}


==E==
{{glossary}}
{{term|[[Biology:Electron transport chain|electron transport chain]]}}
{{defn|}}

{{term|[[Biology:Electroporation|electroporation]]}}
{{ghat|Also '''electropermeabilization'''.}}
{{defn|A molecular biology technique in which a strong electric field is applied to living cells in order to temporarily increase the permeability of their cell membranes, allowing exogenous nucleic acids, proteins, or chemical compounds to easily pass through the membrane and thereby enter the cells. It is a common method of achieving {{gli|transformation}} and {{gli|transfection}}.}}

{{term|elongation}}
{{ghat|Also '''extension'''.}}
{{defn|The linear growth of a {{gli|glossary=Glossary of genetics (M−Z)|nucleic acid}} polymer by the sequential addition of individual {{gli|glossary=Glossary of genetics (M−Z)|nucleotide}} monomers to a {{gli|glossary=Glossary of genetics (M−Z)|nascent}} {{gli|glossary=Glossary of genetics (M−Z)|strand}}, e.g. during {{gli|glossary=Glossary of genetics (M−Z)|transcription}} or {{gli|glossary=Glossary of genetics (M−Z)|replication}}, especially when it occurs by {{gli|complementary pairing}} with a {{gli|glossary=Glossary of genetics (M−Z)|template strand}}. The term is often used to describe steps in certain laboratory techniques such as the {{gli|glossary=Glossary of genetics (M−Z)|polymerase chain reaction}}.}}

{{term|[[Biology:Embryo|embryo]]}}
{{defn|}}

{{term|[[Biology:Emergenesis|emergenesis]]}}
{{defn|The quality of genetic {{gli|glossary=Glossary of genetics (M–Z)|traits}} that results from a specific configuration of interacting {{gli|genes}}, rather than simply their combination.}}

{{term|[[Biology:Endocytosis|endocytosis]]}}
{{defn|}}

{{term|endomembrane}}
{{defn|Any {{gli|plasma membrane|membrane}} surrounding an {{gli|intracellular}} {{gli|organelle}} or {{gli|vesicle}}, e.g. that of the {{gli|endoplasmic reticulum}}, {{gli|Golgi apparatus}}, {{gli|lysosome}}, {{gli|vacuole}}, {{gli|nucleus}} (the {{gli|nuclear envelope}}), etc.<ref name="MacLean"/>}}

{{term|[[Biology:Endonuclease|endonuclease]]}}{{anchor|endonucleases}}
{{defn|Any [[Biology:Enzyme|enzyme]] whose activity is to cleave {{gli|glossary=Glossary of genetics (M–Z)|phosphodiester bonds}} within a chain of {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}}, including those that cleave relatively nonspecifically (without regard to {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence|sequence}}) and those that cleave only at very specific sequences (so-called {{gli|glossary=Glossary of genetics (M–Z)|restriction enzyme|restriction endonucleases}}). When recognition of a specific sequence is required, endonucleases make their cuts in the middle of the sequence. Contrast ''{{gli|exonuclease}}''.}}

<span id="endoplasmic reticulum"></span>{{term|endoplasmic reticulum (ER)}}
{{defn|}}

{{term|[[Biology:Endosome|endosome]]}}
{{defn|}}

{{term|[[Biology:Enhancer (genetics)|enhancer]]}}{{anchor|enhancers}}
{{defn|A region of DNA near a {{gli|gene}} that can be bound by an {{gli|activator}} to increase {{gli|gene expression}} or by a {{gli|glossary=Glossary of genetics (M–Z)|repressor}} to decrease expression.}}

<span id="eRNA"></span>{{term|[[Biology:Enhancer RNA|enhancer RNA]] (eRNA)}}
{{defn|A subclass of {{gli|lncRNA|long non-coding RNAs}} transcribed from regions of DNA containing {{gli|enhancer}} sequences. The expression of a given eRNA generally correlates with the activity of the corresponding enhancer in enhancing transcription of its target genes, suggesting that eRNAs play an active role in gene regulation {{gli|cis|in ''cis''}} or {{gli|glossary=Glossary of genetics (M–Z)|trans|in ''trans''}}.}}

{{term|enucleate}}{{anchor|enucleates|enucleating|enucleated}}
{{defn|To artificially remove the {{gli|nucleus}} from a {{gli|cell}}, e.g. by micromanipulation in the laboratory or by destroying it through irradiation with ultraviolet light, rendering the cell {{gli|anucleate}}.<ref name="MacLean"/>}}

{{term|envagination}}
{{defn|}}

{{term|[[Biology:Epigenetics|epigenetics]]}}{{anchor|epigenetic}}
{{defn|}}

{{term|[[Biology:Epigenome|epigenome]]}}
{{defn|}}

{{term|[[Biology:Episome|episome]]}}{{anchor|episomes|episomal}}
{{defn|no=1|Another name for a {{gli|glossary=Glossary of genetics (M–Z)|plasmid}}, especially one that is capable of integrating into a {{gli|chromosome}}.}}
{{defn|no=2|In [[Biology:Eukaryote|eukaryote]]s, any non-integrated {{gli|extrachromosomal DNA|extrachromosomal}} circular {{gli|DNA}} molecule that is stably maintained and replicated in the {{gli|glossary=Glossary of genetics (M–Z)|nucleus}} simultaneously with the rest of the host cell. Such molecules may include viral genomes, bacterial plasmids, and aberrant chromosomal fragments.}}

{{term|[[Biology:Epistasis|epistasis]]}}{{anchor|epistatic}}
{{defn|The collective action of multiple genes interacting during {{gli|gene expression}}. A form of gene action, epistasis can be either additive or multiplicative in its effects on specific {{gli|glossary=Glossary of genetics (M–Z)|phenotypic traits}}.}}

{{term|ergosome}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|polysome}}''.}}

{{term|[[Biology:Euchromatin|euchromatin]]}}{{anchor|euchromatic}}
{{ghat|Also '''open chromatin'''.}}
{{defn|A relatively open, lightly compacted form of {{gli|chromatin}} in which {{gli|DNA}} is only sporadically bound in {{gli|glossary=Glossary of genetics (M–Z)|nucleosomes}} and thus broadly accessible to binding and manipulation by {{gli|glossary=Glossary of genetics (M–Z)|proteins}} and other molecules. Euchromatic regions of a genome are often enriched in {{gli|genes}} and actively undergoing {{gli|glossary=Glossary of genetics (M–Z)|transcription}}, in contrast to {{gli|heterochromatin}}, which is relatively gene-poor, nucleosome-rich, and less accessible to transcription machinery.}}

{{term|euploidy}}
{{defn|The condition of a cell or organism having an abnormal number of complete sets of {{gli|chromosomes}}, possibly excluding the {{gli|glossary=Glossary of genetics (M–Z)|sex chromosomes}}. Euploidy differs from {{gli|aneuploidy}}, in which a cell or organism has an abnormal number of one or more specific individual chromosomes.}}

{{term|[[Biology:Evolution|evolution]]}}
{{defn|The change in the {{gli|heredity|heritable}} characteristics of biological populations over successive generations. In the most traditional sense, it occurs by changes in the frequencies of {{gli|alleles}} in a population's {{gli|gene pool}}.}}

{{term|''[[Biology:Ex vivo|ex vivo]]''}}
{{defn|}}

{{term|excision}}
{{defn|The enzymatic removal of a polynucleotide sequence from one or more strands of a {{gli|nucleic acid}}, or of a polypeptide sequence from a {{gli|protein}}, typically implying both the breaking of the polymeric molecule in two locations and the subsequent rejoining of the two breakpoints after the sequence between them has been removed. The term may be used to describe a wide variety of processes performed by distinct enzymes, including most {{gli|splicing}} and {{gli|DNA repair}} pathways.<ref name="DoG7"/>}}

{{term|[[Biology:Exocytosis|exocytosis]]}}
{{defn|}}

{{term|[[Biology:Exome|exome]]}}
{{defn|The entire set of {{gli|exons}} within a particular {{gli|genome}}, including {{gli|glossary=Glossary of genetics (M–Z)|untranslated regions}} of mature mRNAs as well as {{gli|coding regions}}.}}

{{term|[[Biology:Exon|exon]]}}{{anchor|exons}}
{{defn|Any part of a {{gli|gene}} that encodes a part of the final mature {{gli|glossary=Glossary of genetics (M–Z)|mRNA|messenger RNA}} produced by that gene after {{gli|introns}} have been removed by {{gli|alternative splicing}}. The term refers to both the sequence as it exists within a DNA molecule and to the corresponding sequence in RNA transcripts.}}

{{term|[[Biology:Exon skipping|exon skipping]]}}
{{defn|}}

{{term|[[Biology:Exonuclease|exonuclease]]}}{{anchor|exonucleases}}
{{defn|Any {{gli|enzyme}} whose activity is to cleave {{gli|glossary=Glossary of genetics (M–Z)|phosphodiester bonds}} within a chain of {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}}, including those that cleave only upon recognition of a specific sequence (so-called {{gli|glossary=Glossary of genetics (M–Z)|restriction enzyme|restriction exonucleases}}). Exonucleases make their cuts at either the {{gli|3'-end|3'}} or {{gli|5'-end}} of the sequence (rather than in the middle, as with {{gli|endonucleases}}).}}

{{term|exosome}}
{{defn|no=1|([[Biology:Exosome complex|protein complex]]) An intracellular multi-protein complex which serves the function of degrading various types of {{gli|RNA}} molecules.}}
{{defn|no=2|([[Biology:Exosome (vesicle)|vesicle]]) A type of membrane-bound {{gli|extracellular vesicle}} produced in many eukaryotic cells by the inward budding of an {{gli|endosome}} and the subsequent fusion of the endosome with the {{gli|plasma membrane}}, causing the release of the vesicle into various extracellular spaces, including biological fluids such as blood and saliva, where they may serve any of a wide variety of physiological functions, from waste management to intercellular signaling.}}

{{term|[[Biology:Exosome complex|exosome complex]]}}
{{defn|An intracellular multi-protein complex which serves the function of degrading various types of {{gli|glossary=Glossary of genetics (M–Z)|RNA}} molecules.}}

{{term|[[Biology:Expression vector|expression vector]]}}
{{ghat|Also '''expression construct'''.}}
{{defn|A type of {{gli|glossary=Glossary of genetics (M–Z)|vector}}, usually a {{gli|glossary=Glossary of genetics (M–Z)|plasmid}} or [[Biology:Viral vector|viral vector]], designed specifically for the {{gli|expression}} of a {{gli|glossary=Glossary of genetics (M–Z)|transgene}} {{gli|insert}} in a target cell, rather than for some other purpose such as {{gli|glossary=Glossary of genetics (M–Z)|molecular cloning|cloning}}.}}
[[File:pET28a-T7-lacO-GFP.svg|thumb|right|Plasmid map of a 3,756-{{gli|base pair|bp}} '''{{gli|expression vector}}''' used in the expression of a {{gli|glossary=Glossary of genetics (M–Z)|transgene}} that makes green fluorescent protein (GFP). The vector also includes a gene for the ''lac'' repressor (lacI) and a gene conferring resistance to the antibiotic kanamycin (KanR), as well as various {{gli|glossary=Glossary of genetics (M–Z)|promoters}} for driving the expression of these genes.]]

{{term|extein}}
{{defn|Any part of an {{gli|amino acid sequence}} which is retained within a precursor {{gli|glossary=Glossary of genetics (M–Z)|polypeptide}}, i.e. not excised by {{gli|glossary=Glossary of genetics (M–Z)|post-translational}} {{gli|glossary=Glossary of genetics (M–Z)|protein splicing}}, and is therefore present in the mature {{gli|glossary=Glossary of genetics (M–Z)|protein}}, analogous to the {{gli|exons}} of RNA transcripts. Contrast ''{{gli|intein}}''.}}

{{term|extension}}
{{defn|See ''{{gli|elongation}}''.}}

{{term|extracellular}}
{{defn|Outside the {{gli|plasma membrane}} of a {{gli|cell}} or cells; i.e. located or occurring externally to a cell. Contrast ''{{gli|intracellular}}''; see also ''{{gli|intercellular}}''.}}

{{term|[[Biology:Extracellular matrix|extracellular matrix]] (ECM)}}{{anchor|extracellular matrix}}
{{ghat|Also '''intercellular matrix'''.}}
{{defn|The network of interacting {{gli|macromolecules}} and minerals secreted by and existing outside of and between cells in {{gli|multicellular}} structures such as {{gli|tissues}} and {{gli|biofilms}}, forming a hydrated, mesh-like, semi-solid suspension which not only holds the cells together in an organized fashion but also provides structural and biochemical support, acting as an elastic, compressible buffer against external stresses as well as both regulating and influencing numerous aspects of cell behavior, among them {{gli|cell adhesion}}, {{gli|motility}}, {{gli|cell metabolism|metabolism}}, {{gli|cell division|division}}, and {{gli|cell signaling|cell-to-cell communication}}. The composition and properties of the ECM vary enormously between organisms and tissue types, but generally it takes the form of a {{gli|polysaccharide}} gel in which various fibrous proteins (especially [[Biology:Collagen|collagen]] and [[Biology:Elastin|elastin]]), enzymes, and {{gli|glycoproteins}} are embedded. Cells themselves both produce the matrix components and respond constantly to local matrix composition, a source of environmental feedback which is critical for {{gli|differentiation}}, tissue organization, and development.<ref name="MacLean"/><ref name=ECB>{{cite book | vauthors = Alberts B, Bray D, Hopin K, Johnson A, Lewis J, Raff M, Roberts K, Walter P | title = Essential cell biology | chapter-url = https://archive.org/details/essentialcellbio00albe | chapter-url-access = registration | chapter = Tissues and Cancer | location = New York and London | publisher = Garland Science | year = 2004 | isbn = 978-0-8153-3481-1 }}</ref>}}

{{term|[[Biology:Extrachromosomal DNA|extrachromosomal DNA]]}}
{{ghat|Also '''extranuclear DNA''' and '''cytoplasmic DNA'''.}}
{{defn|Any {{gli|DNA}} that is not found in {{gli|chromosomes}} or in the {{gli|glossary=Glossary of genetics (M–Z)|nucleus}} of a cell and hence is not {{gli|genomic DNA}}. This may include the DNA contained in {{gli|glossary=Glossary of genetics (M–Z)|plasmids}} or {{gli|organelles}} such as {{gli|glossary=Glossary of genetics (M–Z)|mtDNA|mitochondria}} or {{gli|cpDNA|chloroplasts}}, or, in the broadest sense, DNA introduced by [[Biology:Virus|viral infection]]. Extrachromosomal DNA usually shows significant structural differences from nuclear DNA in the same organism.}}

{{glossary end}}


==F==
{{glossary}}
{{term|facultative expression}}
{{defn|The {{gli|glossary=Glossary of genetics (M–Z)|transcription}} of a {{gli|gene}} only as needed, as opposed to {{gli|constitutive expression}}, in which a gene is transcribed continuously. A gene that is transcribed as needed is called a ''facultative gene''.}}

{{term|[[Chemistry:Fatty acid|fatty acid]]}}
{{defn|}}

{{term|[[Biology:Fermentation|fermentation]]}}
{{defn|}}

{{term|filopodium}}{{anchor|filopodia}}
{{defn|}}

{{term|five-prime cap}}
{{defn|See ''{{gli|5' cap}}''.}}

{{term|five-prime end}}
{{defn|See ''{{gli|5'-end}}''.}}

{{term|five-prime untranslated region}}
{{defn|See ''{{gli|5' untranslated region}}''.}}

{{term|[[Biology:Fixation (population genetics)|fixation]]}}
{{defn|The process by which a single {{gli|allele}} for a particular {{gli|gene}} with multiple different alleles increases in {{gli|allele frequency|frequency}} in a given population such that it becomes permanently established at 100% frequency – that is, the only allele at that {{gli|locus}} within the population's {{gli|gene pool}}. In the absence of {{gli|glossary=Glossary of genetics (M–Z)|mutation}} and {{gli|heterozygote advantage}}, any given allele is eventually destined to become either permanently fixed over all other variants or completely lost from the population, though how long this takes depends on {{gli|glossary=Glossary of genetics (M–Z)|natural selection|selection}} pressures and {{gli|genetic drift|chance fluctuations}} in allele frequencies.}}

{{term|flagellate}}
{{defn|(of a cell) Having one or more {{gli|flagella}}.}}

{{term|[[Biology:Flagellum|flagellum]]}}{{anchor|flagella}}
{{defn|}}

<span id="fISH"></span>{{term|[[Biology:Fluorescence in situ hybridization|fluorescence in situ hybridization]] (FISH)}}
{{defn|}}

{{term|[[Biology:Forward genetics|forward genetics]]}}
{{defn|An experimental approach in {{gli|glossary=Glossary of genetics (M−Z)|molecular genetics}} in which a researcher starts with a specific known {{gli|glossary=Glossary of genetics (M−Z)|phenotype}} and attempts to determine the genetic basis of that phenotype by any of a variety of laboratory techniques, commonly by {{gli|glossary=Glossary of genetics (M−Z)|mutagenesis|inducing}} random {{gli|glossary=Glossary of genetics (M−Z)|mutations}} in the organism's genome and then {{gli|screening}} for changes in the phenotype of interest. Observed phenotypic changes are assumed to have resulted from the mutation(s) present in the screened sample, which can then be {{gli|mapped}} to specific genomic {{gli|loci}} and ultimately to one or more specific {{gli|candidate genes}}. This methodology contrasts with {{gli|reverse genetics}}, in which a specific gene or its gene product is individually manipulated in order to identify the gene's function.}}

{{term|forward mutation}}
{{defn|}}

{{term|[[Biology:Frameshift mutation|frameshift mutation]]}}
{{defn|A type of {{gli|glossary=Glossary of genetics (M–Z)|mutation}} in a {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence}} caused by the {{gli|insertion}} or {{gli|deletion}} of a number of {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} that is not divisible by three. Because of the triplet nature by which nucleotides code for amino acids, a mutation of this sort causes a shift in the {{gli|glossary=Glossary of genetics (M–Z)|reading frame}} of the nucleotide sequence, resulting in the sequence of {{gli|codons}} downstream of the mutation site being completely different from the original.}}

{{term|freeze-drying}}
{{defn|See ''{{gli|lyophilization}}''.}}

<span id="fGED"></span>{{term|[[Organization:FGED Society|Functional Genomics Data (FGED) Society]]}}
{{ghat|Formerly known by the abbreviation '''MGED'''.}}
{{defn|An organization that works with others "to develop standards for biological research data quality, annotation and exchange" as well as software tools that facilitate their use.<ref name="urlFGED Homepage">{{cite web | url = http://fged.org/ | title = Functional Genomics Data Society – FGED Society }}</ref>}}

{{glossary end}}


==G==
{{glossary}}
{{term|[[Biology:G banding|G banding]]}}
{{ghat|Also '''Giemsa banding''' or '''G-banding'''.}}
{{defn|A technique used in {{gli|cytogenetics}} to produce a visible {{gli|karyotype}} by staining the condensed chromosomes with [[Giemsa stain]]. The staining produces consistent and identifiable patterns of dark and light "bands" in regions of {{gli|chromatin}}, which allows specific chromosomes to be easily distinguished.}}

<span id="G1"></span>{{term|G1}}
{{defn|}}

<span id="G2"></span>{{term|G2}}
{{defn|}}

{{term|[[Biology:Gamete|gamete]]}}{{anchor|gametes|gametic|gametic cell|gametic cells|gametogenesis}}
{{defn|A {{gli|haploid}} cell that is the {{gli|glossary=Glossary of genetics (M–Z)|meiotic}} product of a progenitor {{gli|germ cell}} and the final product of the {{gli|germ line}} in sexually reproducing multicellular organisms. Gametes are the means by which an organism passes its genetic information to its offspring; during fertilization, two gametes (one from each parent) are fused into a single {{gli|diploid}} {{gli|glossary=Glossary of genetics (M–Z)|zygote}}.}}

{{term|[[Biology:Gametogenesis|gametogenesis]]}}
{{defn|}}

{{term|GC content}}
{{defn|See ''{{gli|guanine-cytosine content}}''.}}

{{term|gDNA}}
{{defn|See ''{{gli|genomic DNA}}''.}}

{{term|[[Biology:Gene|gene]]}}{{anchor|genes}}
{{defn|Any segment or set of segments of a {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} molecule that contains the information necessary to produce a functional {{gli|glossary=Glossary of genetics (M–Z)|RNA}} transcript in a controlled manner. In living organisms, genes are often considered the fundamental units of {{gli|heredity}} and are typically encoded in {{gli|DNA}}. A particular gene can have multiple different versions, or {{gli|alleles}}, and a single gene can result in a {{gli|gene product}} that influences many different {{gli|glossary=Glossary of genetics (M–Z)|phenotypes}}.}}

{{term|[[Biology:Gene dosage|gene dosage]]}}
{{defn|The number of copies of a particular {{gli|gene}} present in a {{gli|genome}}. Gene dosage directly influences the amount of {{gli|gene product}} a cell is able to express, though a variety of controls have evolved which tightly {{gli|gene regulation|regulate}} {{gli|gene expression}}. Changes in gene dosage caused by mutations include {{gli|copy-number variations}}.}}

{{term|[[Biology:Gene duplication|gene duplication]]}}{{anchor|duplication|duplicate|duplicates|duplicated|duplicating}}
{{ghat|Also '''gene amplification'''.}}
{{defn|A type of {{gli|glossary=Glossary of genetics (M–Z)|mutation}} defined as any {{gli|duplication}} of a region of {{gli|DNA}} that contains a {{gli|gene}}. Compare ''{{gli|chromosomal duplication}}''.}}

{{term|[[Biology:Gene expression|gene expression]]}}{{anchor|express|expression|expressed|expressing}}
{{defn|The set of processes by which the information encoded in a {{gli|gene}} is used in the synthesis of a {{gli|gene product}}, such as a protein or {{gli|glossary=Glossary of genetics (M–Z)|ncRNA|non-coding RNA}}, or otherwise made available to influence one or more {{gli|glossary=Glossary of genetics (M–Z)|phenotypes}}. Canonically, the first step is {{gli|glossary=Glossary of genetics (M–Z)|transcription}}, which produces a {{gli|glossary=Glossary of genetics (M–Z)|messenger RNA}} molecule complementary to the {{gli|DNA}} molecule in which the gene is encoded; for protein-coding genes, the second step is {{gli|glossary=Glossary of genetics (M–Z)|translation}}, in which the messenger RNA is read by the {{gli|glossary=Glossary of genetics (M–Z)|ribosome}} to produce a {{gli|glossary=Glossary of genetics (M–Z)|protein}}. The information contained within a DNA sequence need not necessarily be transcribed and translated to exert an influence on molecular events, however; broader definitions encompass a huge variety of other ways in which genetic information can be expressed.}}

{{term|Gene Expression Omnibus (GEO)}}
{{defn|A database of {{gli|high-throughput}} functional genomics and {{gli|gene expression}} data derived from experimental chips and {{gli|glossary=Glossary of genetics (M–Z)|next-generation sequencing}} and managed by the [[Organization:National Center for Biotechnology Information|National Center for Biotechnology Information]].<ref>{{cite journal |last1=Edgar |first1=R |last2=Domrachev |first2=M |last3=Lash |first3=AE |title=Gene Expression Omnibus: NCBI gene expression and hybridization array data repository. |journal=Nucleic Acids Research |date=1 January 2002 |volume=30 |issue=1 |pages=207–10 |doi=10.1093/nar/30.1.207 |pmid=11752295|pmc=99122 }}</ref><ref>{{cite journal |last1=Barrett |first1=T |last2=Wilhite |first2=SE |last3=Ledoux |first3=P |last4=Evangelista |first4=C |last5=Kim |first5=IF |last6=Tomashevsky |first6=M |last7=Marshall |first7=KA |last8=Phillippy |first8=KH |last9=Sherman |first9=PM |last10=Holko |first10=M |last11=Yefanov |first11=A |last12=Lee |first12=H |last13=Zhang |first13=N |last14=Robertson |first14=CL |last15=Serova |first15=N |last16=Davis |first16=S |last17=Soboleva |first17=A |title=NCBI GEO: archive for functional genomics data sets--update. |journal=Nucleic Acids Research |date=January 2013 |volume=41 |issue=Database issue |pages=D991-5 |doi=10.1093/nar/gks1193 |pmid=23193258|pmc=3531084 }}</ref>}}

{{term|gene fusion}}
{{defn|The union, either by natural mutation or by {{gli|glossary=Glossary of genetics (M–Z)|recombinant DNA|recombinant}} laboratory techniques, of two or more previously independent genes that code for different gene products such that they become subject to control by the same {{gli|gene regulation|regulatory}} systems. The resulting hybrid sequence is known as a {{gli|fusion gene}}.<ref name="DoG7"/>}}

{{term|[[Biology:Gene mapping|gene mapping]]}}
{{defn|Any of a variety of methods used to precisely identify the {{gli|locus|location}} of a particular {{gli|gene}} within a DNA molecule (such as a chromosome) and/or the physical or {{gli|linkage}} distances between it and other genes.}}

<span id="gene of interest"></span>{{term|gene of interest (GOI)}}{{anchor|genes of interest}}
{{defn|A {{gli|gene}} being studied in a scientific experiment, especially one that is the focus of a {{gli|genetic engineering}} technique such as {{gli|glossary=Glossary of genetics (M–Z)|molecular cloning|cloning}}.}}

{{term|[[Biology:Gene product|gene product]]}}{{anchor|gene products|products}}
{{defn|Any of the biochemical material resulting from the {{gli|expression}} of a {{gli|gene}}, most commonly interpreted as the functional {{gli|glossary=Glossary of genetics (M–Z)|mRNA|mRNA transcript}} produced by {{gli|glossary=Glossary of genetics (M–Z)|transcription}} of the gene or the fully constructed {{gli|glossary=Glossary of genetics (M–Z)|protein}} produced by {{gli|glossary=Glossary of genetics (M–Z)|translation}} of the transcript, though {{gli|glossary=Glossary of genetics (M–Z)|ncRNA|non-coding RNA}} molecules such as {{gli|glossary=Glossary of genetics (M–Z)|tRNA|transfer RNAs}} may also be considered gene products. A measurement of the quantity of a given gene product that is detectable in a cell or tissue is sometimes used to infer how active the corresponding gene is.}}

{{term|gene regulation}}{{anchor|regulation|regulate|regulating|regulated|regulatory}}
{{defn|The broad range of mechanisms used by cells to control the activity of their genes, especially to allow, prohibit, increase, or decrease the production or {{gli|expression}} of specific {{gli|gene products}}, such as {{gli|glossary=Glossary of genetics (M–Z)|RNA}} or {{gli|glossary=Glossary of genetics (M–Z)|proteins}}. Gene regulation increases an organism's versatility and adaptability by allowing its cells to express different gene products when required by changes in its environment. In multicellular organisms, the regulation of gene expression also drives [[Biology:Cellular differentiation|cellular differentiation]] and [[Biology:Morphogenesis|morphogenesis]] in the [[Biology:Embryo|embryo]], enabling the creation of a diverse array of cell types from the same {{gli|genome}}.}}

{{term|[[Biology:Gene silencing|gene silencing]]}}{{anchor|silencing}}
{{defn|Any mechanism of {{gli|gene regulation}} which drastically reduces or completely prevents the {{gli|expression}} of a particular gene. Gene silencing may occur naturally during either {{gli|glossary=Glossary of genetics (M–Z)|transcription}} or {{gli|glossary=Glossary of genetics (M–Z)|translation}}. Laboratory techniques often exploit natural silencing mechanisms to achieve {{gli|gene knockdown}}.}}

{{term|[[Biology:Gene therapy|gene therapy]]}}
{{defn|The insertion of a functional or {{gli|glossary=Glossary of genetics (M–Z)|wild-type}} gene or part of a gene into an organism (especially a patient) with the intention of correcting a {{gli|genetic disorder|genetic defect}}, either by direct substitution of the defective gene or by supplementation with a second, functional version.<ref name="Rieger"/>}}

{{term|[[Biology:Gene trapping|gene trapping]]}}
{{defn|A {{gli|high-throughput}} technology used to simultaneously inactivate, identify, and report the {{gli|expression}} of a target gene in a mammalian genome by introducing an insertional {{gli|glossary=Glossary of genetics (M–Z)|mutation}} consisting of a {{gli|glossary=Glossary of genetics (M–Z)|promoter|promoterless}} {{gli|glossary=Glossary of genetics (M–Z)|reporter}} gene and/or a selectable {{gli|genetic marker}} flanked by an upstream {{gli|gene splicing|splice}} site and a downstream {{gli|glossary=Glossary of genetics (M–Z)|polyadenylated}} termination sequence.}}

{{term|generation}}{{anchor|generations}}
{{defn|no=1|In any given organism, a single [[Biology:Biological life cycle|reproductive cycle]], or the phase between two consecutive reproductive events, i.e. between an individual organism's reproduction and that of the progeny of that reproduction; or the actual or average length of time required to complete a single reproductive cycle, either for a particular {{gli|lineage}} or for a population or species as a whole.}}
{{defn|no=2|In a given population, those individuals (often but not necessarily living contemporaneously) who are equally removed from a given {{gli|common ancestor}} by virtue of the same number of reproductive events having occurred between them and the ancestor.<ref name="Rieger"/>}}

{{term|genetic background}}{{anchor|genetic backgrounds}}
{{defn|}}

{{term|[[Biology:Genetic code|genetic code]]}}
{{defn|A set of rules by which information encoded within {{gli|glossary=Glossary of genetics (M–Z)|nucleic acids}} is {{gli|glossary=Glossary of genetics (M–Z)|translated}} into {{gli|glossary=Glossary of genetics (M–Z)|proteins}} by living [[Biology:Cell|cells]]. These rules define how sequences of {{gli|glossary=Glossary of genetics (M–Z)|nucleotide}} triplets called {{gli|codons}} specify which {{gli|amino acid}} will be added next during {{gli|glossary=Glossary of genetics (M–Z)|translation|protein synthesis}}. The vast majority of living organisms use the same genetic code (sometimes referred to as the {{gli|glossary=Glossary of genetics (M–Z)|standard genetic code|"standard" genetic code}}) but [[Biology:Genetic code#Variations|variant codes]] do exist.}}

{{term|[[Medicine:Genetic disorder|genetic disorder]]}}{{anchor|genetic disorders}}
{{defn|Any illness, disease, or other health problem directly caused by one or more abnormalities in an organism's {{gli|genome}} which are congenital (present at birth) and not acquired later in life. Causes may include a {{gli|glossary=Glossary of genetics (M–Z)|mutation}} to one or more {{gli|genes}}, or a {{gli|chromosomal abnormality}} such as an {{gli|aneuploidy}} of a particular chromosome. The mutation responsible {{gli|de novo mutation|may occur spontaneously}} during embryonic development or may be {{gli|heredity|inherited}} from one or both parents, in which case the genetic disorder is also classified as a {{gli|hereditary disorder}}. Though the abnormality itself is present before birth, the actual disease it causes may not develop until much later in life; some genetic disorders do not necessarily guarantee eventual disease but simply {{gli|genetic predisposition|increase the risk}} of developing it.}}

{{term|[[Biology:Genetic distance|genetic distance]]}}
{{defn|A measure of the genetic divergence between species, populations within a species, or individuals, used especially in {{gli|glossary=Glossary of genetics (M–Z)|phylogenetics}} to express either the time elapsed since the existence of a {{gli|glossary=Glossary of genetics and evolutionary biology|common ancestor}} or the degree of differentiation in the {{gli|DNA sequences}} comprising the {{gli|genomes}} of each population or individual.}}

{{term|[[Biology:Genetic engineering|genetic engineering]]}}
{{ghat|Also '''genetic modification''' or '''genetic manipulation'''.}}
{{defn|The direct, deliberate manipulation of an organism's genetic material using any of a variety of biotechnology methods, including the insertion or {{gli|knockout|removal}} of {{gli|genes}}, the transfer of genes within and between species, the {{gli|glossary=Glossary of genetics (M–Z)|mutation}} of existing sequences, and the construction of novel sequences using {{gli|artificial gene synthesis}}. Genetic engineering encompasses a broad set of technologies by which the genetic composition of individual cells, tissues, or entire organisms may be altered for various purposes, commonly in order to study the functions and {{gli|expression}} of individual genes, to produce hormones, vaccines, and other drugs, and to create {{gli|genetically modified organism|genetically modified organisms}} for use in research and agriculture.}}

{{term|[[Biology:Genetic marker|genetic marker]]}}{{anchor|genetic markers|marker|markers}}
{{defn|A specific, easily identifiable, and usually highly {{gli|glossary=Glossary of genetics (M–Z)|polymorphism|polymorphic}} {{gli|gene}} or other {{gli|DNA}} {{gli|glossary=Glossary of genetics (M–Z)|sequence}} with a known location on a {{gli|chromosome}} that can be used to identify the individual or species possessing it.}}

{{term|[[Biology:Genetic recombination|genetic recombination]]}}
{{defn|Any reassortment or exchange of genetic material within an individual organism or between individuals of the same or different species, especially that which creates {{gli|genetic variation}}. In the broadest sense, the term encompasses a diverse class of naturally occurring mechanisms by which {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequences}} are copied or physically transferred into different genetic environments, including {{gli|homologous recombination}} during {{gli|glossary=Glossary of genetics (M–Z)|meiosis}} or {{gli|glossary=Glossary of genetics (M–Z)|mitosis}} or as a normal part of {{gli|DNA repair}}; {{gli|horizontal gene transfer}} events such as {{gli|conjugation|bacterial conjugation}}, {{gli|glossary=Glossary of genetics (M–Z)|transduction|viral transduction}}, or {{gli|glossary=Glossary of genetics (M–Z)|transformation}}; or errors in {{gli|DNA replication}} or cell division. Artificial recombination is central to many {{gli|genetic engineering}} techniques which produce {{gli|glossary=Glossary of genetics (M–Z)|recombinant DNA}}.}}

{{term|[[Biology:Genetic redundancy|genetic redundancy]]}}
{{defn|The redundant encoding of two or more distinct {{gli|gene products}} that ultimately perform the same biochemical function. {{gli|glossary=Glossary of genetics (M–Z)|mutation|Mutations}} in one of these genes may have a smaller effect on fitness than might be expected, since the redundant genes often compensate for any {{gli|loss of function}} and obviate any {{gli|gain of function}}.}}

<span id="genetic regulatory network"></span>{{term|genetic regulatory network (GRN)}}
{{defn|A [[Graph theory|graph]] that represents the regulatory complexity of {{gli|gene expression}}. The vertices (nodes) are represented by various regulatory elements and {{gli|gene products}} while the edges (links) are represented by their interactions. These network structures also represent functional relationships by approximating the rate at which genes are {{gli|glossary=Glossary of genetics (M–Z)|transcribed}}.}}

{{term|[[Medicine:Genetic testing|genetic testing]]}}
{{ghat|Also '''DNA testing''' or '''genetic screening'''.}}
{{defn|A broad class of various procedures used to identify features of an individual's particular chromosomes, genes, or proteins in order to determine parentage or ancestry, diagnose vulnerabilities to heritable diseases, or detect {{gli|glossary=Glossary of genetics (M–Z)|mutant}} alleles associated with increased risks of developing {{gli|genetic disorders}}. Genetic testing is widely used in human medicine, agriculture, and biological research.}}

<span id="genetically modified organism"></span>{{term|[[Biology:Genetically modified organism|genetically modified organism]] (GMO)}}
{{defn|Any organism whose genetic material has been altered using {{gli|genetic engineering}} techniques, particularly in a way that does not occur naturally by mating or by natural {{gli|genetic recombination}}.}}

{{term|[[Biology:Genetics|genetics]]}}
{{defn|The field of [[Biology:Biology|biology]] that studies {{gli|genes}}, {{gli|genetic variation}}, and {{gli|heredity}} in living organisms.}}

{{term|[[Biology:Genome|genome]]}}{{anchor|genomes|genomic}}
{{defn|The entire complement of genetic material contained within the {{gli|chromosomes}} of an organism, [[Biology:Organelle|organelle]], or [[Biology:Virus|virus]]. The term is also used to refer to the collective set of genetic {{gli|loci}} shared by every member of a population or species, regardless of the different {{gli|alleles}} that may be present at these loci in different individuals.}}

{{term|[[Biology:Genome size|genome size]]}}
{{defn|The total amount of {{gli|DNA}} contained within one copy of a {{gli|genome}}, typically measured by [[Physics:Mass|mass]] (in picograms or [[Dalton (unit)|daltons]]) or by the total number of {{gli|base pairs}} (in {{gli|kilobases}} or {{gli|glossary=Glossary of genetics (M–Z)|megabases}}). For {{gli|diploid}} organisms, genome size is often used interchangeably with {{gli|C-value}}.}}

<span id="genomic DNA"></span>{{term|[[Biology:Genomic DNA|genomic DNA]] (gDNA)}}
{{ghat|Also '''chromosomal DNA'''.}}
{{defn|The {{gli|DNA}} contained in {{gli|chromosomes}}, as opposed to the {{gli|extrachromosomal DNA}} contained in separate structures such as {{gli|glossary=Glossary of genetics (M–Z)|plasmids}} or organelles such as {{gli|glossary=Glossary of genetics (M–Z)|mtDNA|mitochondria}} or {{gli|cpDNA|chloroplasts}}.}}

{{term|[[Biology:Genomic imprinting|genomic imprinting]]}}
{{defn|An {{gli|epigenetic}} phenomenon that causes {{gli|genes}} to be {{gli|expressed}} in a manner dependent upon the particular parent from which the gene was inherited. It occurs when epigenetic marks such as {{gli|DNA methylation|DNA}} or {{gli|histone methylation}} are established or "imprinted" in the {{gli|germ cells}} of a parent organism and subsequently maintained through cell divisions in the {{gli|glossary=Glossary of genetics (M–Z)|somatic cells}} of the organism's progeny; as a result, a gene in the progeny that was inherited from the father may be expressed differently than another copy of the same gene that was inherited from the mother.}}

{{term|[[Biology:Genomic island|genomic island]]}}
{{defn|}}

{{term|[[Biology:Genomics|genomics]]}}
{{defn|An interdisciplinary field that studies the structure, function, evolution, mapping, and editing of entire {{gli|genomes}}, as opposed to individual {{gli|genes}}.}}

{{term|[[Biology:Genotoxicity|genotoxicity]]}}
{{defn|The ability of certain chemical agents to cause damage to genetic material within a living cell (e.g. through single- or double-stranded breaks, {{gli|crosslinking}}, or {{gli|glossary=Glossary of genetics (M–Z)|point mutations}}), which may or may not result in a permanent {{gli|glossary=Glossary of genetics (M–Z)|mutation}}. Though all {{gli|glossary=Glossary of genetics (M–Z)|mutagens}} are genotoxic, not all genotoxic compounds are mutagenic.}}

{{term|[[Biology:Genotype|genotype]]}}{{anchor|genotypes}}
{{defn|The entire complement of {{gli|alleles}} present in a particular individual's {{gli|genome}}, which gives rise to the individual's {{gli|glossary=Glossary of genetics (M–Z)|phenotype}}.}}

{{term|[[Biology:Genotyping|genotyping]]}}
{{defn|The process of determining differences in the {{gli|genotype}} of an individual by examining the {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence|DNA sequences}} in the individual's {{gli|genome}} using [[Earth:Bioassay|bioassay]]s and comparing them to another individual's sequences or a reference sequence.}}

{{term|[[Biology:Germ cell|germ cell]]}}{{anchor|germ cells}}
{{defn|Any {{gli|cell}} that gives rise to the {{gli|gametes}} of a [[Biology:Sexual reproduction|sexually reproducing]] organism. Germ cells are the vessels for the genetic material which will ultimately be passed on to the organism's descendants and are usually distinguished from {{gli|glossary=Glossary of genetics (M–Z)|somatic cells}}, which are entirely separate from the {{gli|germ line}}.}}

{{term|germ line}}
{{defn|no=1|In multicellular organisms, the subpopulation of cells which are capable of passing on their genetic material to the organism's progeny and are therefore (at least theoretically) distinct from {{gli|glossary=Glossary of genetics (M–Z)|somatic cells}}, which cannot pass on their genetic material except to their own immediate {{gli|glossary=Glossary of genetics (M–Z)|mitotic}} daughter cells. Cells of the germ line are called {{gli|germ cells}}.}}
{{defn|no=2|The {{gli|lineage}} of germ cells, spanning many generations, that contains the genetic material which has been passed on to an individual from its ancestors.}}

<span id="gigabase"></span>{{term|gigabase (Gb)}}{{anchor|gigabases|Gb|Gbp}}
{{defn|A unit of {{gli|glossary=Glossary of cellular and molecular biology (M–Z)|nucleic acid}} length equal to one billion (1,000,000,000) {{gli|glossary=Glossary of cellular and molecular biology (M–Z)|nucleobase|bases}} in {{gli|glossary=Glossary of genetics (M–Z)|single-stranded}} molecules or one billion {{gli|base pairs}} in duplex molecules such as {{gli|dsDNA|double-stranded DNA}}.}}

{{term|[[Chemistry:Glucogenic amino acid|glucogenic amino acid]]}}{{anchor|glucogenic amino acids}}
{{defn|Any {{gli|amino acid}} that can be converted into {{gli|glucose}} via {{gli|gluconeogenesis}}, as opposed to the {{gli|ketogenic amino acids}}, which can be converted into ketone bodies. In humans, 18 of the 20 amino acids are glucogenic; only [[Chemistry:Leucine|leucine]] and [[Chemistry:Lysine|lysine]] are not. Five amino acids ([[Chemistry:Phenylalanine|phenylalanine]], [[Chemistry:Isoleucine|isoleucine]], [[Chemistry:Threonine|threonine]], [[Chemistry:Tryptophan|tryptophan]], and [[Chemistry:Tyrosine|tyrosine]]) are both glucogenic and ketogenic.}}

{{term|[[Biology:Gluconeogenesis|gluconeogenesis]] (GNG)}}{{anchor|gluconeogenesis}}
{{defn|The chain of {{gli|metabolic}} reactions that results in the generation of {{gli|glucose}} from some non-carbohydrate carbon substrates, including the {{gli|glucogenic amino acids}}. It is one of two primary pathways used by most animals to maintain blood sugar levels (the other being {{gli|glycogenolysis}}), especially during periods of fasting, starvation, and intense exercise.}}

{{term|[[Biology:Glycogen|glycogen]]}}
{{defn|}}

{{term|[[Biology:Glycogenolysis|glycogenolysis]]}}
{{defn|}}

{{term|[[Biology:Glycolysis|glycolysis]]}}
{{defn|}}

{{term|[[Chemistry:Glycoside|glycoside]]}}{{anchor|glycosides}}
{{defn|Any chemical compound in which a {{gli|carbohydrate}} molecule is covalently bonded to another molecule containing a hydroxyl group (including other carbohydrates) via one or more {{chem|C|–|O}} {{gli|glycosidic bonds}}. When both molecules are carbohydrates, the glycoside is a {{gli|disaccharide}} or {{gli|polysaccharide}}.<ref name="MacLean"/>}}

{{term|[[Chemistry:Glycosidic bond|glycosidic bond]]}}{{anchor|glycosidic bonds}}
{{defn|}}

{{term|[[Biology:Glycosylation|glycosylation]]}}{{anchor|glycosylate|glycosylates|glycosylated|glycosylating}}
{{defn|The attachment of an {{gli|oligosaccharide}} (e.g. {{gli|glucose}}) to an [[Chemistry:Asparagine|asparagine]] residue within a {{gli|peptide}} or {{gli|protein}} by covalent bonding, a process which takes place in or near the {{gli|rough endoplasmic reticulum}}.<ref name="MacLean"/>}}

{{term|Goldberg-Hogness box}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|TATA box}}''.}}

{{term|[[Biology:Golgi apparatus|Golgi apparatus]]}}
{{defn|}}

{{term|gRNA}}
{{defn|See ''{{gli|guide RNA}}''.}}

<span id="guanine"></span>{{term|term=[[Chemistry:Guanine|guanine]]|content=[[Chemistry:Guanine|guanine]] ({{font|G|font=courier|size=large}})}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|purine}} {{gli|glossary=Glossary of genetics (M–Z)|nucleobase}} used as one of the four standard nucleobases in both {{gli|DNA}} and {{gli|glossary=Glossary of genetics (M–Z)|RNA}} molecules. Guanine forms a {{gli|base pair}} with {{gli|cytosine}}.}}

{{term|guanine-cytosine content}}
{{ghat|Also abbreviated '''GC-content'''.}}
{{defn|The proportion of {{gli|glossary=Glossary of genetics (M–Z)|nitrogenous base|nitrogenous bases}} in a {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} that are either {{gli|guanine}} ({{font|G|font=courier|size=big}}) or {{gli|cytosine}} ({{font|C|font=courier|size=big}}), typically expressed as a percentage. DNA and RNA molecules with higher GC-content are generally more [[Biology:Thermostability|thermostable]] than those with lower GC-content due to molecular interactions that occur during base stacking.<ref name ="Yakovchuk2006">{{cite journal |vauthors=Yakovchuk P, Protozanova E, Frank-Kamenetskii MD |title=Base-stacking and base-pairing contributions into thermal stability of the DNA double helix |journal=Nucleic Acids Res. |volume=34 |issue=2 |pages=564–74 |year=2006 |pmid=16449200 |pmc=1360284 |doi=10.1093/nar/gkj454 |url=}}</ref>}}

<span id="guanosine"></span>{{term|term=[[Chemistry:Guanosine|guanosine]]|content=[[Chemistry:Guanosine|guanosine]] ({{font|G|font=courier|size=large}}, Guo)}}
{{defn|One of the four standard {{gli|glossary=Glossary of genetics (M–Z)|nucleosides}} used in {{gli|glossary=Glossary of genetics (M–Z)|RNA}} molecules, consisting of a {{gli|guanine}} {{gli|base}} with its N<sub>9</sub> nitrogen {{gli|glycosidic bond|bonded}} to the C<sub>1</sub> carbon of a {{gli|glossary=Glossary of genetics (M–Z)|ribose}} sugar. Guanine bonded to {{gli|deoxyribose}} is known as {{gli|deoxyguanosine}}, which is the version used in {{gli|DNA}}.}}

<span id="gRNA"></span>{{term|[[Biology:Guide RNA|guide RNA]] (gRNA)}}
{{defn|}}

{{glossary end}}


==H==
{{glossary}}
{{term|hairpin}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|stem-loop}}''.}}

{{term|[[Biology:Haploid|haploid]]}}
{{ghat|Denoted in shorthand with the somatic number '''''n'''''.}}
{{defn|(of a [[Biology:Cell|cell]] or organism) Having one copy of each {{gli|chromosome}}, with each copy not being part of a pair. Contrast ''{{gli|diploid}}'' and ''{{gli|glossary=Glossary of genetics (M–Z)|polyploid}}''.}}

{{term|[[Biology:Hayflick limit|Hayflick limit]]}}
{{defn|}}

{{term|[[Biology:Helicase|helicase]]}}{{anchor|helicases}}
{{defn|Any of a class of [[Chemistry:Adenosine triphosphate|ATP]]-dependent motor proteins that move directionally along the {{gli|DNA}} {{gli|glossary=Glossary of genetics (M–Z)|phosphodiester backbone|backbone}} and catalyze the separation of the two complementary {{gli|glossary=Glossary of genetics (M–Z)|strands}} of {{gli|double-stranded}} molecules, permitting a wide variety of vital processes to take place, e.g. {{gli|glossary=Glossary of genetics (M–Z)|transcription}}, {{gli|DNA replication|replication}}, and {{gli|DNA repair|repair}}.<ref name="Rieger"/>}}

{{term|hemizygous}}
{{defn|In a {{gli|diploid}} organism, having just one {{gli|allele}} at a given {{gli|locus|genetic locus}} (where there would ordinarily be two). Hemizygosity may be observed when only one copy of a {{gli|chromosome}} is present in a normally diploid cell or organism, or when a segment of a chromosome containing one copy of an allele is {{gli|deletion|deleted}}, or when a gene is located on a {{gli|allosome|sex chromosome}} in the [[Biology:Heterogametic sex|heterogametic sex]] (in which the sex chromosomes do not exist in matching pairs); for example, in human males with normal chromosomes, almost all {{gli|glossary=Glossary of genetics (M–Z)|X-linked}} genes are said to be hemizygous because there is only one {{gli|glossary=Glossary of genetics (M–Z)|X chromosome}} and few of the same genes exist on the {{gli|glossary=Glossary of genetics (M–Z)|Y chromosome}}.}}

{{term|[[Biology:Heredity|heredity]]}}{{anchor|inheritance|inherit|inherits|inherited}}
{{ghat|Also '''inheritance'''.}}
{{defn|The storage, transfer, and expression of molecular information in biological organisms,<ref name="Rieger"/> as manifested by the passing on of {{gli|glossary=Glossary of genetics (M–Z)|phenotypic traits}} from parents to their {{gli|glossary=Glossary of genetics (M–Z)|offspring}}, either through [[Biology:Sexual reproduction|sexual]] or asexual reproduction. Offspring cells or organisms are said to ''inherit'' the genetic information of their parents.}}

{{term|[[Biology:Heterochromatin|heterochromatin]]}}{{anchor|heterochromatic}}
{{defn|}}

{{term|heterochromosome}}
{{defn|See ''{{gli|allosome}}''.}}

{{term|heterodimer}}
{{defn|A {{gli|glossary=Glossary of genetics (M−Z)|protein}} or protein {{gli|domain}} composed of two different {{gli|glossary=Glossary of genetics (M−Z)|polypeptides}} which are {{gli|dimer|paired with each other}} in the quaternary structure of a multimeric complex.<ref name="DoG7"/> Contrast ''{{gli|homodimer}}''.}}

{{term|heterogeneous nuclear RNA (hnRNA)}}{{anchor|hnRNA|heterogeneous nuclear RNA}}
{{defn|}}

{{term|[[Biology:Heterokaryon|heterokaryon]]}}
{{defn|A {{gli|multinucleate}} cell containing {{gli|nuclei}} with different genotypes, resulting from the {{gli|cell fusion|fusion}} of two or more genetically distinct cells, either naturally (e.g. in certain types of [[Biology:Sexual reproduction|sexual reproduction]]) or artificially (e.g. in [[Biology:Genetic engineering|genetic engineering]]).<ref name="MacLean"/>}}

{{term|[[Biology:Heterologous expression|heterologous expression]]}}
{{defn|The {{gli|expression}} of a foreign {{gli|gene}} or any other foreign DNA sequence within a host organism which does not naturally contain the same gene. Insertion of foreign {{gli|glossary=Glossary of genetics (M–Z)|transgenes}} into heterologous hosts using {{gli|glossary=Glossary of genetics (M–Z)|recombinant DNA|recombinant}} {{gli|glossary=Glossary of genetics (M–Z)|vectors}} is a common biotechnology method for studying gene structure and function.}}

{{term|heterozygous}}{{anchor|heterozygote|heterozygosity}}
{{defn|In a {{gli|diploid}} organism, having two different {{gli|alleles}} at a given {{gli|locus|genetic locus}}. In genetics shorthand, heterozygous {{gli|genotypes}} are represented by a pair of non-matching letters or symbols, often an uppercase letter (indicating a {{gli|dominant}} allele) and a lowercase letter (indicating a {{gli|glossary=Glossary of genetics (M–Z)|recessive}} allele), such as "Aa" or "Bb". Contrast ''{{gli|homozygous}}''.}}

{{term|high-throughput}}
{{defn|}}

{{term|[[Biology:Histology|histology]]}}{{anchor|histological}}
{{defn|The study or analysis of the microscopic anatomy of biological {{gli|tissues}} or of {{gli|cells}} within tissues, particularly by making use of specialized techniques to distinguish structures and functions based on visual morphology and differential staining. In practice the term is sometimes used more broadly to include {{gli|cytology}}.}}

{{term|[[Biology:Histone|histone]]}}{{anchor|histones}}
{{defn|Any of a class of highly [[Chemistry:Alkaline|alkaline]] {{gli|proteins}} responsible for {{gli|DNA condensation|packaging}} {{gli|glossary=Glossary of genetics (M–Z)|nuclear}} DNA into structural units called {{gli|glossary=Glossary of genetics (M–Z)|nucleosomes}} in eukaryotic cells. Histones are the chief protein components of {{gli|chromatin}}, where they associate into {{gli|histone core|eight-membered complexes}} which act as "spools" around which the linear DNA molecule winds. They play a major role in {{gli|gene regulation}} and {{gli|expression}}.}}

{{term|histone core}}
{{ghat|Also '''histone octamer''' and '''core particle'''.}}
{{defn|The complex of eight {{gli|histone}} proteins around which double-stranded DNA wraps within a {{gli|glossary=Glossary of genetics (M−Z)|nucleosome}}. The canonical histone octamer consists of two each of histones [[Biology:Histone H2A|H2A]], [[Biology:Histone H2B|H2B]], H3, and [[Biology:Histone H4|H4]], which pair with each other symmetrically to form a ball-shaped cluster around which DNA winds through interactions with the histones' surface {{gli|domains}}, though {{gli|histone variant|variant histones}} may replace their analogues in certain contexts.}}

{{term|histone modification}}
{{defn|}}

{{term|histone variant}}
{{defn|}}

{{term|hnRNA}}
{{defn|See ''{{gli|heterogeneous nuclear RNA}}''.}}

{{term|holocentric}}
{{defn|(of a linear {{gli|chromosome}} or chromosome fragment) Having no single {{gli|centromere}} but rather multiple {{gli|kinetochore}} assembly sites dispersed along the entire length of the chromosome. During cell division, the {{gli|chromatids}} of holocentric chromosomes move apart in parallel and do not form the classical V-shaped structures typical of {{gli|glossary=Glossary of genetics (M–Z)|monocentric}} chromosomes.}}

{{term|[[Biology:Homeobox|homeobox]]}}{{anchor|homeoboxes}}
{{defn|Any of a class of DNA {{gli|glossary=Glossary of genetics (M−Z)|sequences}} approximately 180 base pairs in length occurring near the {{gli|3'‐end}} of certain eukaryotic genes and encoding a {{gli|homeodomain|60-amino acid domain}} which is capable of {{gli|DNA-binding domain|binding to DNA or RNA}} via a characteristic helix-turn-helix motif in proteins containing it. Homeobox-containing genes are translated into homeodomain-containing proteins, which commonly {{gli|gene regulation|regulate}} transcription or translation by binding to other genes or messenger RNAs containing specific {{gli|homeobox responsive elements}}. The products of many homeotic genes, exemplified by the {{gli|Hox genes}}, are of critical importance in developmental pathways.<ref name="DoG7"/>}}

{{term|homeobox responsive element (HRE)}}{{anchor|homeodomain responsive element|homeobox responsive elements}}
{{ghat|Also '''homeodomain responsive element'''.}}
{{defn|Any DNA or RNA {{gli|glossary=Glossary of genetics (M−Z)|sequence}} that is specifically {{gli|glossary=Glossary of genetics (M−Z)|recognition sequence|recognized}} and bound by the {{gli|homeodomain}} of a homeodomain-containing protein.}}

{{term|homeodomain}}{{anchor|homeodomains}}
{{defn|A type of {{gli|DNA-binding domain|nucleic acid-binding domain}}, typically 60 {{gli|amino acids}} in length, found in certain eukaryotic {{gli|glossary=Glossary of genetics (M−Z)|proteins}}, characterized by a highly {{gli|conserved}} helix-turn-helix {{gli|glossary=Glossary of genetics (M−Z)|motif}} that binds with strong affinity to the backbone of specific {{gli|glossary=Glossary of genetics (M−Z)|recognition sequences}} in DNA or RNA molecules. A protein may have one or more homeodomains, generally situated towards the {{gli|C-terminus}} of the polypeptide containing it. Many homeodomain-containing proteins function as {{gli|glossary=Glossary of genetics (M−Z)|transcription factors}} by binding to sequences within {{gli|glossary=Glossary of genetics (M−Z)|promoters}} and blocking or recruiting other proteins, such as {{gli|glossary=Glossary of genetics (M−Z)|RNA polymerase}}, to the {{gli|glossary=Glossary of genetics (M−Z)|transcription initiation complex}}. Homeodomains are the {{gli|glossary=Glossary of genetics (M−Z)|translated}} versions of {{gli|homeoboxes}}, though the terms are often used interchangeably.}}

{{term|homodimer}}
{{defn|A {{gli|glossary=Glossary of genetics (M−Z)|protein}} or protein {{gli|domain}} composed of two identical {{gli|glossary=Glossary of genetics (M−Z)|polypeptides}} which are {{gli|dimer|paired with each other}} in the quaternary structure of a multimeric complex.<ref name="DoG7"/> Contrast ''{{gli|heterodimer}}''.}}

{{term|homologous chromosomes}}{{anchor|homologous chromosome}}
{{ghat|Also '''homologs''' or '''homologues'''.}}
{{defn|A set of two matching {{gli|chromosomes}}, one maternal and one paternal, which pair up with each other inside the nucleus during {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}. They have the same {{gli|genes}} at the same {{gli|loci}}, but may have different {{gli|alleles}}.}}

{{term|[[Biology:Homologous recombination|homologous recombination]]}}
{{defn|A type of {{gli|genetic recombination}} in which nucleotide sequences are exchanged between two similar or identical ("homologous") molecules of {{gli|DNA}}, especially that which occurs between {{gli|homologous chromosomes}}. The term may refer to the recombination that occurs as a part of any of a number of distinct cellular processes, most commonly {{gli|DNA repair}} or {{gli|chromosomal crossover}} during {{gli|glossary=Glossary of genetics (M–Z)|meiosis}} in eukaryotes and {{gli|horizontal gene transfer}} in prokaryotes. Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|nonhomologous recombination}}''.}}

{{term|homozygous}}{{anchor|homozygote|homozygotes|homozygosity|homozygotic}}
{{defn|In a {{gli|diploid}} organism, having two identical {{gli|alleles}} at a given {{gli|locus|genetic locus}}. In genetics shorthand, homozygous {{gli|genotypes}} are represented by a pair of matching letters or symbols, such as "AA" or "aa". Contrast ''{{gli|heterozygous}}''.}}

<span id="HGT"></span>{{term|[[Biology:Horizontal gene transfer|horizontal gene transfer]] (HGT)}}
{{ghat|Also '''lateral gene transfer (LGT)'''.}}
{{defn|Any process by which genetic material is transferred between unicellular and/or multicellular organisms other than by vertical transmission from parent to offspring, e.g. [[Biology:Bacterial conjugation|bacterial conjugation]].}}

{{term|[[Biology:Housekeeping gene|housekeeping gene]]}}{{anchor|housekeeping genes}}
{{defn|Any {{gli|constitutive expression|constitutive gene}} that is {{gli|glossary=Glossary of genetics (M–Z)|transcribed}} at a relatively constant level across many or all known conditions and cell types. The {{gli|gene product|products}} of housekeeping genes typically play critical roles in the maintenance of cellular integrity and basic metabolic function. It is generally assumed that their expression is unaffected by experimental or pathological conditions.}}

{{term|Hox genes}}
{{defn|A subset of highly {{gli|conserved}} {{gli|homeobox}}-containing {{gli|genes}} which are essential for the proper organization of the [[Biology:Body plan|body plan]] in developing animal embryos, ensuring that the correct structures are formed in the correct places. Hox genes are usually arranged on a chromosome in {{gli|glossary=Glossary of genetics (M–Z)|tandem}} arrays and are {{gli|expressed}} sequentially during development, with the sequence of gene activation corresponding to their physical arrangement within the genome and/or the physical layout of the tissues in which they are expressed along the organism's anterior–posterior axis.<ref name="DoG7"/>}}

<span id="HGP"></span>{{term|[[Biology:Human Genome Project|Human Genome Project]] (HGP)}}
{{defn|A collaborative international scientific research project with the goal of {{gli|glossary=Glossary of genetics (M–Z)|sequencing}} all of the {{gli|genomic DNA|chromosomal DNA}} and identifying and {{gli|gene mapping|mapping}} all of the {{gli|genes}} within human cells, and ultimately of assembling a complete {{gli|glossary=Glossary of genetics (M–Z)|reference genome}} for the human species. The project was launched in 1990 by a consortium of federal agencies, universities, and research institutions and was declared complete in 2003. Because each individual human being has a unique genome, the finished reference genome is a {{gli|mosaic}} of sequences obtained by sampling DNA from thousands of individuals across the world and does not represent any one individual.}}

{{term|hyaloplasm}}
{{defn|See ''{{gli|cytosol}}''.}}

{{term|[[Biology:Hybrid|hybrid]]}}{{anchor|hybrids}}
{{defn|The {{gli|glossary=Glossary of genetics (M–Z)|offspring}} that results from combining the qualities of two organisms of different [[Biology:Genus|genera]], [[Biology:Species|species]], [[Biology:Breed|breed]]s, or varieties through [[Biology:Sexual reproduction|sexual reproduction]]. Hybrids may occur naturally or artificially, as during {{gli|glossary=Glossary of genetics (M–Z)|selective breeding}} of domesticated animals and plants. Reproductive barriers typically prevent hybridization between distantly related organisms, or at least ensure that hybrid offspring are sterile, but fertile hybrids may result in [[Biology:Speciation|speciation]].}}

{{term|[[Biology:Nucleic acid thermodynamics#Hybridization|hybridization]]}}
{{defn|no=1|The process by which a {{gli|hybrid}} organism is produced from two organisms of different genera, species, breeds, or varieties.}}
{{defn|no=2|The process by which two or more {{gli|glossary=Glossary of genetics (M–Z)|single-stranded}} {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} molecules with {{gli|complementary}} nucleotide sequences {{gli|glossary=Glossary of genetics (M–Z)|pair}} with each other in solution, creating {{gli|double-stranded}} or {{gli|glossary=Glossary of genetics (M–Z)|triple-stranded}} molecules via the formation of [[Chemistry:Hydrogen bond|hydrogen bond]]s between the complementary nucleobases of each strand. In certain laboratory contexts, especially ones in which long strands hybridize with short {{gli|glossary=Glossary of genetics (M–Z)|oligonucleotide}} {{gli|glossary=Glossary of genetics (M–Z)|primers}}, hybridization is often referred to as {{gli|annealing}}.}}
{{defn|no=3|A step in some experimental assays in which a single-stranded DNA or RNA preparation is added to an array surface and {{gli|anneals}} to a {{gli|complementary}} {{gli|glossary=Glossary of genetics (M–Z)|probe}}.}}

{{term|[[Biology:Hybridization probe|hybridization probe]]}}
{{defn|}}

<span id="hypoxanthine"></span>{{term|term=[[Chemistry:Hypoxanthine|hypoxanthine]]|content=[[Chemistry:Hypoxanthine|hypoxanthine]] ({{font|I|font=courier|size=large}})}}
{{defn|A naturally occurring non-canonical {{gli|glossary=Glossary of genetics (M–Z)|purine}} {{gli|glossary=Glossary of genetics (M–Z)|nucleobase}} that is used in some {{gli|glossary=Glossary of genetics (M–Z)|RNA}} molecules and pairs with standard nucleobases in a phenomenon known as {{gli|glossary=Glossary of genetics (M–Z)|wobble base pairing}}. Its {{gli|glossary=Glossary of genetics (M–Z)|nucleoside}} form is known as {{gli|inosine}}, which is the reason it is commonly abbreviated with the letter {{font|I|font=courier|size=big}} in sequence reads.}}

{{glossary end}}


==I==
{{glossary}}
{{term|idiochromosome}}
{{defn|See ''{{gli|allosome}}''.}}

{{term|idiogram}}
{{ghat|Also '''ideogram'''.}}
{{defn|A diagrammatic or schematic {{gli|karyotype}} of the entire set of {{gli|chromosomes}} within a cell or genome, in which annotated illustrations depict each chromosome in its most idealized form (e.g. with straight lines and obvious {{gli|centromeres}}) so as to facilitate the easy identification of sequences, structural features, and physical distances, which may be less apparent in photomicrographs of the actual chromosomes.}}

{{term|idiomere}}
{{defn|See ''{{gli|chromomere}}''.}}

{{term|immunogenic}}
{{defn|}}

{{term|[[Biology:Immunohistochemistry|immunohistochemistry]] (IHC)}}{{anchor|immunohistochemistry}}
{{defn|}}

{{term|[[Biology:Immunostaining|immunostaining]]}}
{{defn|}}

{{term|''[[Biology:In silico|in silico]]''}}
{{defn|(of a scientific experiment or research) Conducted, produced, or analyzed by means of computer modeling or simulation, as opposed to a real-world trial.}}

{{term|''[[Biology:In situ|in situ]]''}}
{{defn|(of a scientific experiment or biological process) Occurring or made to occur in a natural, uncontrolled setting, or in the natural or original position or place, as opposed to in a foreign cell or tissue type or {{gli|in vitro|in an artificial environment}}.}}

{{term|[[Biology:In situ hybridization|''in situ'' hybridization]]}}
{{defn|}}

{{term|''[[In vitro|in vitro]]''}}
{{defn|(of a scientific experiment or biological process) Occurring or made to occur in a laboratory vessel or other controlled artificial environment, e.g. in a test tube or a petri dish, as opposed to {{gli|in vivo|inside a living organism}} or {{gli|in situ|in a natural setting}}.}}

{{term|''[[Biology:In vivo|in vivo]]''}}
{{defn|(of a scientific experiment or biological process) Occurring or made to occur inside the cells or tissues of a living organism; or, in the broadest sense, in any natural, unmanipulated setting. Contrast ''{{gli|ex vivo}}'' and ''{{gli|in vitro}}''.}}

{{term|[[Biology:Indel|indel]]}}{{anchor|indels}}
{{defn|A term referring to either an {{gli|insertion|'''in'''sertion}} or a {{gli|deletion|'''del'''etion}} of one or more {{gli|glossary=Glossary of genetics (M–Z)|nucleobase|bases}} in a nucleic acid sequence.}}

{{term|[[Biology:Inducer|inducer]]}}{{anchor|inducers}}
{{defn|A protein that binds to a {{gli|glossary=Glossary of genetics (M–Z)|repressor}} (to disable it) or to an {{gli|activator}} (to enable it).}}

{{term|inducible gene}}
{{defn|A {{gli|gene}} whose {{gli|expression}} is either responsive to environmental change or dependent on its host cell's position within the [[Biology:Cell cycle|cell cycle]].}}

{{term|in-frame}}
{{defn|no=1|(of a gene or sequence) Read or transcribed in the same {{gli|glossary=Glossary of genetics (M–Z)|reading frame}} as another gene or sequence; not requiring a shift in reading frame to be intelligible or to result in a functional {{gli|glossary=Glossary of genetics (M–Z)|peptide}}.}}
{{defn|no=2|(of a mutation) Not causing a {{gli|frameshift mutation|frameshift}}.<ref name="DoG7"/>}}

{{term|inheritance}}
{{defn|See ''{{gli|heredity}}''.}}

{{term|initiation codon}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|start codon}}''.}}

{{term|[[Chemistry:Inosine|inosine]]}}
{{defn|}}

{{term|[[Biology:Insertion (genetics)|insertion]]}}{{anchor|insertional|inserted|inserting}}
{{defn|A type of {{gli|glossary=Glossary of genetics (M–Z)|mutation}} in which one or more {{gli|glossary=Glossary of genetics (M–Z)|nucleobase|bases}} are added to a {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence}}. Contrast ''{{gli|deletion}}''.}}

<span id="insertion sequence"></span>{{term|[[Biology:Insertion sequence|insertion sequence]] (IS)}}{{anchor|insertion sequences|insert|inserts}}
{{ghat|Also '''insertion element''' or simply '''insert'''.}}
{{defn|Any nucleotide sequence that is {{gli|insertion|inserted}} naturally or artificially into another sequence. The term is used in particular to refer to the part of a {{gli|glossary=Glossary of genetics (M–Z)|transposable element}} that codes for those proteins directly involved in the transposition process, e.g. the {{gli|glossary=Glossary of genetics (M–Z)|transposase}} enzyme. The coding region in a transposable insertion sequence is usually flanked by short {{gli|inverted repeat|inverted repeats}}, and the structure of larger transposable elements may include a pair of flanking insertion sequences which are themselves inverted.}}

{{term|[[Biology:Insertional mutagenesis|insertional mutagenesis]]}}
{{defn|The alteration of a DNA sequence by the {{gli|insertion}} of one or more nucleotides into the sequence, either naturally or artificially. Depending on the precise location of the insertion within the target sequence, insertions may partially or totally inactivate or even upregulate a {{gli|gene product}} or biochemical pathway, or they may be {{gli|glossary=Glossary of genetics (M–Z)|neutral mutation|neutral}}, leading to no substantive changes at all. Many {{gli|genetic engineering}} techniques rely on the insertion of exogenous genetic material into host cells in order to study gene function and expression.<ref name="DoG7"/>}}

{{term|[[Biology:Insulator (genetics)|insulator]]}}
{{defn|A specific DNA sequence that prevents a gene from being influenced by the {{gli|activation}} or {{gli|glossary=Glossary of genetics (M–Z)|repression}} of nearby genes.}}

{{term|[[Biology:Integral membrane protein|integral membrane protein]]}}
{{defn|}}

{{term|integration}}
{{defn|}}

{{term|[[Biology:Integron|integron]]}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|mobile genetic element}} consisting of a {{gli|gene cassette}} containing the gene for a {{gli|glossary=Glossary of genetics (M–Z)|site-specific recombination|site-specific recombinase}}, {{gli|integrase}}-specific recognition sites, and a {{gli|glossary=Glossary of genetics (M–Z)|promoter}} that governs the expression of one or more genes conferring adaptive traits on the host cell. Integrons usually exist in the form of circular {{gli|episomal}} DNA fragments, through which they facilitate the rapid adaptation of bacteria by enabling {{gli|horizontal gene transfer}} of antibiotic resistance genes between different bacterial species.<ref name="DoG7"/>}}

{{term|[[Biology:Intein|intein]]}}
{{defn|Any sequence of one or more {{gli|amino acids}} within a precursor {{gli|glossary=Glossary of genetics (M–Z)|polypeptide}} that is excised by {{gli|glossary=Glossary of genetics (M–Z)|protein splicing}} during {{gli|glossary=Glossary of genetics (M–Z)|post-translational modification}} and is therefore absent from the mature {{gli|glossary=Glossary of genetics (M–Z)|protein}}, analogous to the {{gli|introns}} spliced out of RNA transcripts.<ref name="DoG7"/> Contrast ''{{gli|extein}}''.}}

{{term|intercalating agent}}
{{defn|Any chemical compound (e.g. [[Chemistry:Ethidium bromide|ethidium bromide]]) that disrupts the alignment and {{gli|base pair|pairing of bases}} in the complementary strands of a {{gli|DNA}} molecule by {{gli|intercalation|inserting itself between the bases}}.<ref name="CoG"/>}}

{{term|[[Chemistry:Intercalation (biochemistry)|intercalation]]}}
{{defn|The insertion, naturally or artificially, of chemical compounds between the planar {{gli|bases}} of a {{gli|DNA}} molecule, which generally disrupts the hydrogen bonding necessary for {{gli|base pairing}}.}}

{{term|intercellular}}
{{defn|Between two or more {{gli|cells}}. Contrast ''{{gli|intracellular}}''; see also ''{{gli|extracellular}}''.}}

{{term|intercistronic region}}
{{defn|Any DNA sequence that is located between the {{gli|glossary=Glossary of genetics (M–Z)|stop codon}} of one {{gli|gene}} and the {{gli|glossary=Glossary of genetics (M–Z)|start codon}} of the following gene in a {{gli|glossary=Glossary of genetics (M–Z)|polycistronic}} transcription unit.<ref name="DoG7"/> See also ''{{gli|intergenic region}}''.}}

{{term|intercross}}
{{defn|A {{gli|cross}} in which both the male and female parents are {{gli|heterozygous}} at a particular {{gli|locus}}.<ref name="DoG7"/>}}

<span id="intergenic region"></span>{{term|[[Biology:Intergenic region|intergenic region]] (IGR)}}
{{defn|Any sequence of {{gli|glossary=Glossary of genetics (M–Z)|ncDNA|non-coding DNA}} that is located between functional {{gli|genes}}.}}

{{term|intergenic spacer (IGS)}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|spacer}}''.}}

{{term|[[Biology:Interkinesis|interkinesis]]}}
{{ghat|Also '''interphase II'''.}}
{{defn|The abbreviated pause in activities related to cell division that occurs during {{gli|glossary=Glossary of genetics (M–Z)|meiosis}} in some species, between the first and second meiotic divisions (i.e. meiosis I and meiosis II). No {{gli|DNA replication}} occurs during interkinesis, unlike during the normal {{gli|interphase}} that precedes meiosis I and {{gli|glossary=Glossary of genetics (M–Z)|mitosis}}.<ref name="DoG7"/>}}

<span id="internal ribosome entry site"></span>{{term|[[Biology:Internal ribosome entry site|internal ribosome entry site]] (IRES)}}
{{defn|A sequence present in some {{gli|glossary=Glossary of genetics (M−Z)|messenger RNAs}} that permits recognition by the {{gli|glossary=Glossary of genetics (M−Z)|ribosome}} and thus the initiation of {{gli|glossary=Glossary of genetics (M−Z)|translation}} even in the absence of a {{gli|5' cap}}, which in eukaryotes is otherwise required for assembly of the initiation complex. IRES elements are often located in the {{gli|5' untranslated region}}, but may also be found in other positions.}}

{{term|[[Biology:Interphase|interphase]]}}
{{defn|All stages of the [[Biology:Cell cycle|cell cycle]] excluding [[Biology:Cell division|cell division]]. A typical cell spends most of its life in interphase, during which it conducts everyday metabolic activities as well as the complete {{gli|DNA replication|replication}} of its genome in preparation for {{gli|glossary=Glossary of genetics (M–Z)|mitosis}} or {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}.}}

{{term|intracellular}}
{{defn|Within a {{gli|cell}} or cells; i.e. inside the {{gli|plasma membrane}}. Contrast ''{{gli|intercellular}}'' and ''{{gli|extracellular}}''.}}

{{term|[[Biology:Intracellular space|intracellular space]]}}
{{defn|}}

{{term|intragenic region}}
{{defn|See ''{{gli|intron}}''.}}

{{term|intragenic suppression}}
{{defn|}}

{{term|[[Biology:Intragenomic conflict|intragenomic conflict]]}}
{{defn|}}

{{term|[[Biology:Intron|intron]]}}
{{ghat|Also '''intragenic region'''.}}
{{defn|Any {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence|nucleotide sequence}} within a functional {{gli|gene}} that is removed by {{gli|glossary=Glossary of genetics (M–Z)|RNA splicing}} during {{gli|glossary=Glossary of genetics (M–Z)|post-transcriptional modification}} of the {{gli|glossary=Glossary of genetics (M–Z)|mRNA}} {{gli|glossary=Glossary of genetics (M–Z)|primary transcript}} and is therefore absent from the final mature mRNA. The term refers to both the sequence as it exists within a DNA molecule and to the corresponding sequence in RNA transcripts. Contrast ''{{gli|exon}}''.}}

{{term|intron intrusion}}
{{defn|}}

{{term|intron-mediated recombination}}
{{defn|See ''{{gli|exon shuffling}}''.}}

{{term|[[Philosophy:Invagination|invagination]]}}
{{defn|The infolding of a {{gli|membrane}} toward the interior of a cell or organelle, or of a sheet of cells toward the interior of a developing {{gli|embryo}}, {{gli|tissue}}, or organ, forming a distinct membrane-lined pocket. In the case of individual cells, the invaginated pocket may proceed to separate from the source membrane entirely, creating a membrane-bound {{gli|vesicle}} within the cell, as in {{gli|endocytosis}}.<ref name="MacLean"/>}}

{{term|[[Biology:Inverted repeat|inverted repeat]]}}
{{defn|A {{gli|glossary=Glossary of genetics (M–Z)|nucleotide sequence}} followed {{gli|downstream}} on the same {{gli|glossary=Glossary of genetics (M–Z)|strand}} by its own {{gli|glossary=Glossary of genetics (M–Z)|reverse complement}}. The initial sequence and the reverse complement may be separated by any number of nucleotides, or may be immediately adjacent to each other; in the latter case, the composite sequence is also called a {{gli|glossary=Glossary of genetics (M–Z)|palindromic sequence}}. Inverted repeats are {{gli|glossary=Glossary of genetics (M–Z)|self-complementary}} by definition, a property which involves them in many biological functions and dysfunctions. Contrast ''{{gli|direct repeat}}''.}}

{{term|[[Physics:Ionophore|ionophore]]}}
{{defn|Any chemical compound or macromolecule that facilitates the movement of ions across biological membranes, or more specifically, any chemical species that reversibly binds electrically charged atoms or molecules. Many ionophores are lipid-soluble {{gli|proteins}} that catalyze the transport of monovalent and divalent cations across the hydrophobic {{gli|lipid bilayers}} surrounding cells and vesicles.<ref name="MacLean"/>}}

{{term|[[Biology:Isochore (genetics)|isochore]]}}
{{defn|A large region of {{gli|genomic DNA}} with a relatively homogeneous composition of {{gli|base pairs}}, distinguished from other regions by the proportion of pairs that are {{font|{{gli|guanine|G}}|font=courier|size=big}}-{{font|{{gli|cytosine|C}}|font=courier|size=big}} or {{font|{{gli|adenine|A}}|font=courier|size=big}}-{{font|{{gli|glossary=Glossary of genetics (M–Z)|thymine|T}}|font=courier|size=big}}. The genomes of most plants and vertebrates are composed of different classes of GC-rich and AT-rich isochores.<ref name="DoG7"/>}}

{{term|[[Biology:Isochromosome|isochromosome]]}}
{{defn|A type of abnormal {{gli|chromosome}} in which the arms of the chromosome are mirror images of each other. Isochromosome formation is equivalent to simultaneous {{gli|duplication}} and {{gli|deletion}} events such that two copies of either the {{gli|long arm}} or the {{gli|glossary=Glossary of genetics (M–Z)|short arm}} comprise the resulting chromosome.}}

{{term|isomeric genes}}
{{defn|Two or more {{gli|genes}} that are equivalent and redundant in the sense that, despite coding for distinct {{gli|gene product|gene products}}, they each result in the same {{gli|glossary=Glossary of genetics (M–Z)|phenotype}} when set within the same {{gli|genetic background}}. If several isomeric genes are present in a single {{gli|genotype}} they may be either cumulative or non-cumulative in their contributions to the phenotype.<ref name="Rieger"/>}}

{{glossary end}}


==J==
{{glossary}}
{{term|jumping gene}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|transposable element}}''.}}

{{term|[[Biology:Junctional diversity|junctional diversity]]}}
{{defn|}}

{{term|junk DNA}}
{{defn|Any DNA sequence that appears to have no known biological function, or which acts in a way that has no positive or a net negative effect on the fitness of the {{gli|genome}} in which it is located. The term was once more broadly used to refer to all {{gli|glossary=Glossary of genetics (M–Z)|ncDNA|non-coding DNA}}, though much of this was later discovered to have a function; in modern usage it typically refers to broken or vestigial sequences and {{gli|glossary=Glossary of genetics (M–Z)|selfish genetic elements}}, including {{gli|introns}}, {{gli|glossary=Glossary of genetics (M–Z)|pseudogenes}}, {{gli|intergenic region|intergenic DNA}}, and fragments of {{gli|glossary=Glossary of genetics (M–Z)|transposons}} and retroviruses, which together constitute a large proportion of the genomes of most eukaryotes. Despite not contributing productively to the host organism, these sequences are able to persist indefinitely inside genomes because the disadvantages of continuing to copy them are too small to be acted upon by {{gli|glossary=Glossary of genetics (M–Z)|natural selection}}.}}

{{term|junk RNA}}
{{defn|Any RNA-encoded sequence, especially a {{gli|glossary=Glossary of genetics (M–Z)|transcript}}, that appears to have no known biological function, or whose function has no positive or a net negative effect on the fitness of the genome from which it is transcribed. Despite remaining {{gli|glossary=Glossary of genetics (M–Z)|translation|untranslated}}, many {{gli|glossary=Glossary of genetics (M–Z)|ncRNA|non-coding RNAs}} still serve important functions, whereas junk RNAs are truly useless: often they are the product of accidental transcription of a {{gli|junk DNA}} sequence, or they may result from {{gli|glossary=Glossary of genetics (M–Z)|post-transcriptional modification|post-transcriptional processing}} of {{gli|glossary=Glossary of genetics (M–Z)|primary transcripts}}, as with {{gli|alternative splicing|spliced-out}} {{gli|introns}}. Junk RNA is usually quickly degraded by {{gli|glossary=Glossary of genetics (M–Z)|ribonucleases}} and other cytoplasmic enzymes.}}

{{glossary end}}


==K==
{{glossary}}
{{term|karyogram}}
{{defn|A {{gli|karyotype}} which depicts the entire set of {{gli|chromosomes}} in a cell or organism by using photomicrographs of the actual chromosomes as they appear ''{{gli|in vivo}}'' (usually during {{gli|glossary=Glossary of genetics (M−Z)|metaphase}}, in their most condensed forms), as opposed to the idealized illustrations of chromosomes used in {{gli|idiograms}}. The photomicrographs are often still arranged in pairs and by size for easier identification of particular chromosomes, whereas in the actual nucleus there is seldom any apparent organization.}}

{{term|karyon}}
{{defn|See ''{{gli|nucleus}}''.}}

{{term|[[Biology:Karyotype|karyotype]]}}{{anchor|karyotypes}}
{{defn|The number and appearance of {{gli|chromosomes}} within the {{gli|glossary=Glossary of genetics (M–Z)|nucleus}} of a eukaryotic cell, especially as depicted in an organized {{gli|karyogram}} or {{gli|idiogram}} (in pairs and arranged by size and by position of the {{gli|centromere}}). The term is also used to refer to the complete set of chromosomes in a species or individual organism or to any test that detects this complement or measures the chromosome number.}}
[[File:NHGRI human male karyotype.png|thumb|right|The '''{{gli|karyotype}}''' of a typical human male, as visualized in a karyogram using {{gli|G banding|Giemsa staining}}]]

{{term|[[Biology:Ketogenesis|ketogenesis]]}}
{{defn|}}

{{term|[[Chemistry:Ketogenic amino acid|ketogenic amino acid]]}}{{anchor|ketogenic amino acids}}
{{defn|Any {{gli|amino acid}} that can be converted directly into {{gli|acetyl-CoA}}, which can then be oxidized for energy or used as a precursor for many {{gli|ketone bodies|compounds containing ketone groups}}. This is in contrast to the {{gli|glucogenic amino acids}}, which can be converted into {{gli|glucose}}. In humans, seven of the 20 amino acids are ketogenic, though only [[Chemistry:Leucine|leucine]] and [[Chemistry:Lysine|lysine]] are exclusively ketogenic; the other five ([[Chemistry:Phenylalanine|phenylalanine]], [[Chemistry:Isoleucine|isoleucine]], [[Chemistry:Threonine|threonine]], [[Chemistry:Tryptophan|tryptophan]], and [[Chemistry:Tyrosine|tyrosine]]) are both ketogenic and glucogenic.}}

{{term|[[Chemistry:Ketolysis|ketolysis]]}}
{{defn|}}

<span id="kilobase"></span>{{term|kilobase (kb)}}{{anchor|kilobases|kb|kbp}}
{{defn|A unit of {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid}} length equal to 1,000 {{gli|glossary=Glossary of genetics (M–Z)|nucleobase|bases}} in {{gli|glossary=Glossary of genetics (M–Z)|single-stranded}} molecules or 1,000 {{gli|base pairs}} in duplex molecules such as {{gli|dsDNA|double-stranded DNA}}.}}

{{term|[[Biology:Kinase|kinase]]}}{{anchor|kinases}}
{{defn|Any of a class of {{gli|enzymes}} which catalyze the transfer of {{gli|phosphate}} groups from high-energy, phosphate-donating molecules such as {{gli|ATP}} to one or more specific {{gli|substrates}}, a process known as {{gli|phosphorylation}}. The opposite process, known as {{gli|dephosphorylation}}, is catalyzed by {{gli|phosphatase}} enzymes.}}

{{term|[[Philosophy:Kinesis|kinesis]]}}
{{defn|Any movement or change in activity by a cell or a population of cells in response to a stimulus, such that the rate of the movement or activity is dependent on the intensity of the stimulus but not on the direction from which the stimulus occurs. Kinesis is often defined as any non-specific, non-directional response, in contrast to {{gli|taxis}} and {{gli|tropism}}.}}

{{term|[[Biology:Kinetochore|kinetochore]]}}{{anchor|kinetochores}}
{{defn|A disc-shaped protein complex which assembles around the {{gli|centromere}} of a {{gli|chromosome}} during {{gli|glossary=Glossary of genetics (M–Z)|prometaphase}} of {{gli|glossary=Glossary of genetics (M–Z)|mitosis}} and {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}, where it functions as the attachment point for microtubules of the {{gli|glossary=Glossary of genetics (M–Z)|spindle apparatus}}.}}

{{term|knob}}
{{defn|In {{gli|cytogenetics}}, an enlarged, heavily staining {{gli|chromomere}} that can be used as a visual marker, allowing specific chromosomes to be easily identified in the nucleus.<ref name="DoG7"/>}}

{{term|[[Biology:Gene knockdown|knockdown]]}}
{{defn|A {{gli|genetic engineering}} technique by which the normal rate of {{gli|expression}} of one or more of an organism's {{gli|genes}} is reduced, either through direct modification of a DNA sequence or through treatment with a [[Biology:Reagent|reagent]] such as a short DNA or RNA {{gli|glossary=Glossary of genetics (M–Z)|oligonucleotide}} with a sequence {{gli|complementary}} to either an {{gli|glossary=Glossary of genetics (M–Z)|mRNA}} transcript or a gene.}}

{{term|knockin}}
{{defn|}}

{{term|[[Biology:Gene knockout|knockout]]}}
{{defn|A {{gli|genetic engineering}} technique in which an organism is modified to carry {{gli|genes}} that have been made inoperative ("knocked out"), such that their {{gli|expression}} is disrupted at some point in the pathway that produces their {{gli|gene product|gene products}} and the organism is deprived of their normal effects. Contrast ''{{gli|knockin}}''.}}

{{term|[[Biology:Kozak consensus sequence|Kozak consensus sequence]]}}
{{ghat|Also simply '''Kozak sequence'''.}}
{{defn|A highly {{gli|conserved sequence|conserved}} {{gli|glossary=Glossary of genetics (M–Z)|nucleic acid sequence}} {{gli|glossary=Glossary of genetics (M–Z)|motif}} which functions as the recognition site for the initiation of {{gli|glossary=Glossary of genetics (M–Z)|translation}} in most eukaryotic {{gli|glossary=Glossary of genetics (M–Z)|mRNA|messenger RNAs}}, generally a sequence of 10 bases immediately surrounding and inclusive of the {{gli|glossary=Glossary of genetics (M–Z)|start codon}}: {{font|GCC{{gli|glossary=Glossary of genetics (M–Z)|purine|R}}CCAUGG|font=courier|size=big}}. As the {{gli|glossary=Glossary of genetics (M–Z)|pre-initiation complex}} scans the transcript, recognition of this sequence (or a close variant) causes the complex to commit to full {{gli|glossary=Glossary of genetics (M–Z)|ribosome}} assembly and the start of translation. The Kozak sequence is distinct from other recognition sequences relevant to translation such as {{gli|glossary=Glossary of genetics (M–Z)|ribosome binding site|ribosome binding sites}} and {{gli|internal ribosome entry site|internal ribosome entry sites}}.<ref name="Kozak">{{Cite journal|last=Kozak|first=M.|date=February 1989|title=The scanning model for translation: an update|journal=The Journal of Cell Biology|volume=108|issue=2|pages=229–241|doi=10.1083/jcb.108.2.229|issn=0021-9525|pmc=2115416|pmid=2645293}}</ref>}}

{{term|Krebs cycle}}
{{defn|See ''{{gli|citric acid cycle}}''.}}

{{glossary end}}


==L==
{{glossary}}
{{term|labelling}}
{{ghat|Also '''tagging'''.}}
{{defn|A laboratory technique involving the chemical attachment of a highly selective substance, known as a ''label'', ''tag'', or ''{{gli|glossary=Glossary of genetics (M–Z)|probe}}'', to a particular cell, protein, amino acid, or other biomolecule of interest, either ''{{gli|in vivo}}'' or ''{{gli|in vitro}}''. The label is typically a reactive derivative of a naturally fluorescent compound (e.g. [[Biology:Green fluorescent protein|green fluorescent protein]]) or any other substance that makes its target distinguishable in some way; other commonly used labels include dyes, enzymes, antibodies, and radioactive molecules. The labelled targets are thereby rendered distinct from their surroundings, allowing them to be easily detected, identified, quantified, or isolated for further study.}}

{{term|lagging strand}}
{{defn|In {{gli|DNA replication}}, the nascent {{gli|glossary=Glossary of genetics (M–Z)|strand}} for which {{gli|DNA polymerase}}'s direction of synthesis is away from the {{gli|glossary=Glossary of genetics (M–Z)|replication fork}}, which necessitates a complex and discontinuous process, in contrast to the streamlined, continuous synthesis of the {{gli|leading strand|other nascent strand}} that occurs simultaneously. Because DNA polymerase works only in the {{gli|5'}} to {{gli|3'}} direction, but the overall direction of chain elongation must ultimately be the opposite (i.e. 3' to 5', toward the replication fork), the elongation must occur by an indirect mechanism in which a {{gli|glossary=Glossary of genetics (M–Z)|primase}} synthesizes short {{gli|glossary=Glossary of genetics (M–Z)|RNA}} {{gli|glossary=Glossary of genetics (M–Z)|primers}} complementary to the template DNA, and DNA polymerase then extends the primed segments into short chains of nucleotides known as {{gli|glossary=Glossary of genetics (M–Z)|Okazaki fragments}}. The RNA primers are then removed and replaced with DNA, and the Okazaki fragments are joined by {{gli|DNA ligase}}.}}

{{term|[[Biology:Lampbrush chromosome|lampbrush chromosome]]}}
{{defn|}}

{{term|lateral gene transfer (LGT)}}
{{defn|See ''{{gli|horizontal gene transfer}}''.}}

{{term|[[Biology:Leader sequence (mRNA)|leader sequence]]}}
{{defn|See ''{{gli|5' untranslated region}}''.}}

{{term|leading strand}}
{{defn|In {{gli|DNA replication}}, the nascent {{gli|glossary=Glossary of genetics (M–Z)|strand}} for which both {{gli|DNA polymerase}}'s direction of synthesis and that of the overall chain elongation are toward the {{gli|glossary=Glossary of genetics (M–Z)|replication fork}}, i.e. both occur in the {{gli|5'}} to {{gli|3'}} direction, resulting in a single, continuous elongation process with few or no interruptions. By contrast, the other nascent strand, known as the {{gli|lagging strand}}, is assembled in a discontinuous process involving the ligation of short {{gli|glossary=Glossary of genetics (M–Z)|Okazaki fragment|DNA fragments}} which are synthesized in the opposite direction, away from the replication fork.<ref name="DoG7"/>}}

{{term|left splicing junction}}
{{ghat|Also '''donor splicing junction''' or '''donor splicing site'''.}}
{{defn|The boundary between the left end (by convention, the {{gli|5' end}}) of an {{gli|intron}} and the right ({{gli|3'}}) end of an adjacent {{gli|exon}} in a {{gli|glossary=Glossary of genetics (M–Z)|primary transcript|pre-mRNA transcript}}.}}

{{term|leptonema}}
{{ghat|Also '''leptotene stage'''.}}
{{defn|In {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}, the first of five substages of {{gli|glossary=Glossary of genetics (M–Z)|prophase|prophase I}}, following {{gli|interphase}} and preceding {{gli|glossary=Glossary of genetics (M–Z)|zygonema}}. During leptonema, the replicated chromosomes condense from diffuse {{gli|chromatin}} into long, thin strands that are much more visible within the {{gli|glossary=Glossary of genetics (M–Z)|nucleus}}.}}

{{term|lethal equivalent value}}
{{defn|The average number of {{gli|glossary=Glossary of genetics (M–Z)|recessive}} deleterious genes existing in the {{gli|heterozygous}} condition that is carried by a member of a population of {{gli|diploid}} organisms, multiplied by the average probability that each such gene will cause premature {{gli|lethal|lethality}} when {{gli|homozygous}}. For example, an organism carrying eight recessive {{gli|glossary=Glossary of genetics (M–Z)|semilethal}} alleles, each of which produces only a 50% probability of premature death when homozygous, is said to carry a genetic burden of four "lethal equivalents".<ref name="DoG7"/>}}

{{term|lethal mutation}}
{{defn|Any {{gli|glossary=Glossary of genetics (M–Z)|mutation}} that results in the premature death of the organism carrying it. {{gli|glossary=Glossary of genetics (M–Z)|recessive|Recessive}} lethal mutations are fatal only to {{gli|homozygous|homozygotes}}, whereas {{gli|dominant}} lethals are fatal even in {{gli|heterozygous|heterozygotes}}.<ref name="DoG7"/>}}

{{term|[[Biology:Leucine zipper|leucine zipper]]}}
{{defn|}}

{{term|[[Biology:Ligase|ligase]]}}{{anchor|ligases}}
{{defn|A class of enzymes which catalyze the joining of large molecules such as {{gli|glossary=Glossary of genetics (M–Z)|nucleic acids}} by forming one or more chemical bonds between them, typically {{chem|C–C}}, {{chem|C–O}}, {{chem|C–S}}, or {{chem|C–N}} bonds via [[Chemistry:Condensation reaction|condensation reaction]]s. An example is {{gli|DNA ligase}}, which catalyzes the formation of {{gli|glossary=Glossary of genetics (M–Z)|phosphodiester bonds}} between adjacent {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} on one or both strands of a DNA molecule, a reaction known as {{gli|ligation}}.}}

{{term|[[Biology:Ligation (molecular biology)|ligation]]}}{{anchor|ligations|ligate|ligates|ligated}}
{{defn|}}

{{term|[[Biology:Genetic linkage|linkage]]}}{{anchor|linked|unlinked}}
{{defn|The tendency of DNA sequences which are physically near to each other on the same chromosome to be {{gli|heredity|inherited}} together during {{gli|glossary=Glossary of genetics (M–Z)|meiosis}}. Because the physical distance between them is relatively small, the chance that any two nearby parts of a DNA sequence (often {{gli|loci}} or {{gli|genetic markers}}) will be separated on to different {{gli|chromatids}} during {{gli|chromosomal crossover}} is statistically very low; such loci are then said to be more ''linked'' than loci that are farther apart. Loci that exist on entirely different chromosomes are said to be perfectly ''unlinked''. The standard unit for measuring genetic linkage is the {{gli|centimorgan}} (cM).}}

{{term|[[Biology:Linkage disequilibrium|linkage disequilibrium]]}}
{{defn|}}

{{term|[[Biology:Linker DNA|linker DNA]]}}
{{defn|no=1|A short, synthetic DNA duplex containing the {{gli|glossary=Glossary of genetics (M–Z)|restriction site|recognition sequence}} for a particular {{gli|glossary=Glossary of genetics (M–Z)|restriction enzyme}}.<ref name="DoG7"/> In {{gli|glossary=Glossary of genetics (M–Z)|molecular cloning}}, linkers are often deliberately included in {{gli|glossary=Glossary of genetics (M–Z)|recombinant DNA|recombinant}} molecules in order to make them easily modifiable by permitting cleavage and {{gli|insertion}} of foreign sequences at precise locations. A segment of an engineered {{gli|glossary=Glossary of genetics (M–Z)|plasmid}} containing many such restriction sites is sometimes called a {{gli|glossary=Glossary of genetics (M–Z)|polylinker}}.}}
{{defn|no=2|A section of chromosomal DNA connecting adjacent {{gli|glossary=Glossary of genetics (M–Z)|nucleosomes}} by binding to {{gli|histone}} [[Biology:Histone H1|H1]].<ref name="DoG7"/>}}

{{term|[[Linking number|linking number]]}}
{{defn|The number of times that the two strands of a circular {{gli|double helix|double-helical}} {{gli|DNA}} molecule cross each other, equivalent to the {{gli|glossary=Glossary of genetics (M–Z)|twisting number}} (which measures the torsion of the double helix) plus the {{gli|glossary=Glossary of genetics (M–Z)|writhing number}} (which measures the degree of supercoiling). The linking number of a closed molecule cannot be changed without breaking and rejoining the strands. DNA molecules which are identical except for their linking numbers are known as ''topological isomers''.<ref name="DoG7"/>}}

{{term|lncRNA}}
{{defn|See ''{{gli|lncRNA|long non-coding RNA}}''.}}

{{term|[[Biology:Locus (genetics)|locus]]}}{{anchor|loci}}
{{ghat|Plural '''loci'''.}}
{{defn|A specific, fixed position on a {{gli|chromosome}} where a particular {{gli|gene}} or {{gli|genetic marker}} resides.}}

{{term|LOD score}}
{{defn|}}

{{term|long arm}}{{anchor|long arms}}
{{ghat|Denoted in shorthand with the symbol '''''q'''''.}}
{{defn|In condensed {{gli|chromosomes}} where the positioning of the {{gli|centromere}} creates two segments or "arms" of unequal length, the longer of the two arms of a {{gli|chromatid}}. Contrast ''{{gli|glossary=Glossary of genetics (M–Z)|short arm}}''.}}

<span id="LINE"></span>{{term|[[Biology:Long interspersed nuclear element|long interspersed nuclear element]] (LINE)}}
{{defn|Any of a large family of non-{{gli|LTR}} {{gli|glossary=Glossary of genetics (M–Z)|retrotransposons}} which together comprises one of the most widespread {{gli|glossary=Glossary of genetics (M–Z)|mobile genetic elements}} in eukaryotic genomes. Each LINE {{gli|insertion sequence|insertion}} is on average about 7,000 base pairs in length.}}

<span id="lncRNA"></span>{{term|[[Biology:Long non-coding RNA|long non-coding RNA]] (lncRNA)}}
{{defn|A class of {{gli|glossary=Glossary of genetics (M–Z)|non-coding RNA}} consisting of all {{gli|glossary=Glossary of genetics (M–Z)|transcripts}} of more than 200 {{gli|glossary=Glossary of genetics (M–Z)|nucleotides}} in length that are not {{gli|glossary=Glossary of genetics (M–Z)|translated}}. This limit distinguishes lncRNA from the numerous smaller non-coding RNAs such as {{gli|glossary=Glossary of genetics (M–Z)|microRNA}}. See also ''{{gli|lincRNA|long intervening non-coding RNA}}''.}}

{{term|lyonization}}
{{defn|See ''{{gli|glossary=Glossary of genetics (M–Z)|X-inactivation}}''.}}

{{term|[[Biology:Lysis|lysis]]}}{{anchor|lytic|lysing|lysed}}
{{defn|The disruption and decomposition of the {{gli|plasma membrane}} surrounding a cell, or more generally of any membrane-bound {{gli|organelle}} or {{gli|vesicle}}, especially by osmotic, enzymatic, or other chemical or mechanical processes which compromise the membrane's integrity and thereby cause the unobstructed interchange of the contents of {{gli|intracellular}} and {{gli|extracellular}} spaces. Lysis generally implies the complete and irreversible loss of intracellular organization as a result of the release of the cell's internal components and the dilution of the {{gli|cytosol}}, and therefore the death of the cell. Such a cell is said to be ''lysed'', and a fluid containing the contents of lysed cells (often including {{gli|nucleic acids}}, {{gli|proteins}}, and many other organic molecules) is called a ''lysate''. Lysis may occur both naturally and artificially, and is a normal part of the cellular life cycle.}}

{{term|[[Biology:Lysosome|lysosome]]}}{{anchor|lysosomes}}
{{defn|}}

{{glossary end}}


==See also==
*[[Biology:Introduction to genetics|Introduction to genetics]]
*[[Biology:Outline of genetics|Outline of genetics]]
*[[Biology:Outline of cell biology|Outline of cell biology]]
*Glossary of biology
*Glossary of chemistry
*[[Biology:Glossary of evolutionary biology|Glossary of evolutionary biology]]

==References==
<references />

==Further reading==
*{{cite book |last=Budd |first=A. |title=Evolutionary Genomics |chapter=Introduction to Genome Biology: Features, Processes, and Structures |series=Methods in Molecular Biology |volume=855 |year=2012 |number=855 |pages=3–4|doi=10.1007/978-1-61779-582-4_1 |pmid=22407704 |isbn=978-1-61779-581-7 }}

==External links==
*[https://www.genome.gov/genetics-glossary National Human Genome Research Institute (NHGRI) Talking Glossary of Genetic Terms]

{{Glossaries of science and engineering}}
{{MolBioGeneExp}}

{{DEFAULTSORT:Genetics Glossary}}
[[Category:Genetics|*]]

{{Sourceattribution|Glossary of cellular and molecular biology (0–L)}}